The main work presented in this dissertation is about the design and synthesis of novel BAILs and the study of using them acted as medium/catalysts in Fischer esterifications and the synthesis of 4(3H)-quinazolinones carried out under solvent- free and microwave irradiation conditions.The contents are listed as following: In chapter 2 and 3 of this dissertation, we describe the synthesis of twelve novel acidic ionic liquids using N-methylimidazole, pyridine and benzyl chloride as starting materials involving quaterisation and anion exchange two-step reactions.These BAILs based on N-benzylpyridinium and 1-benzyl-3-methylimidazolium cation, the anions are BF4-, HSO4-, H2PO4-, p-TSA-, CF3COO-, ClCH2COO- respectively. Their viscosity, density, polarity were also characterized, in which N-benzylpyridinium hydrogensulfa te([BYBE][HSO4]),1-benzyl-3-methylimidazolium hydrogensulfate ([MIMBE][HS O4]) and N-benzylpyridinium hydrogenphosphate ([BYBE][ [H2PO4]), 1-benzyl-3- methylimidazolium hydrogen phosphate([MIMBE][H2PO4] represented Brønsted acid ity , the rest represented Lewis acidity. In chapter 4 of this dissertation, eight novel BAILs based on 2,3-pyridinedicarbo xylic acid cation were synthesized and characterized, the synthesis of these ionic liquids using 2,3-pyridinedicarboxylic acid, benzyl chloride, n-butyl bromide as starting materials via quaterisation and anion exchange reactions, the anions are BF4-, CF3COO-, HSO4-, H2PO4- respectively. These BAILs possess strong Brønsted acidity and are liquids at room temperature. In chapter 5 of this dissertation, two novel Brønsted acidic ionic liquids: 1-(4-sul fonic acid benzyl)-3-methylimidazolium hydrogensulfate ([MIMBES][HSO4]) and N -(4-sulfonic acid benzyl)pyridinium hydrogensulfate ([BYBES][HSO4]) were synthe sized and characterized, the synthesis of using 1-benzyl-3-methylimidazolium and N- benzyl pyridinium chlorides as starting material via two synthetic routes.They served as medium and catalyst realized the Fischer esterifications of long chain aliphatic acids (C4～C18) with methanol and ethanol carried out at room temperature under solvent–free conditions, it was found that in the presence of 10mol% ionic liquids reactions carried out smoothly with good to excellent isolated yields(84.6～99%). These ionic liquids could be recovered easily and recycled three times without any significant loss in catalytic activity. [MIMBES][HSO4] gave better results for shorter cabon chain aliphatic acids than [BYBES][HSO4],but for longer carbon chain substrates [BYBES][HSO4] gave better results than [MIMBES][HSO4]. In chapter 6 of this dissertation, the Fischer esterifications of benzoic acid with C3～C16 aliphatic alcohols and C2～C16 aliphatic acids, benzoic acid with benzyl alcohol using [MIMBE][HSO4], [BYBE][HSO4], [MIMBE][H2PO4], and [BYBE][ H2 PO4] as medium and catalyst under solvent-free and microwave irradiation conditions was study. it was found the reactions carried out smoothly without the need of added catalyst with good to excellent isolated yields (77～98.5%) in the presence of 50mol%BAILs. These BAILs could be recovered easily and recycled three times only 1.8～3.4% loss in their catalytic activity. In chapter 7 of this dissertation, the synthesis of 2-substituted-4(3H)-quinazolinon es, 2,3-disubstituted-4(3H)-quinazolinones and 2-substituted-4(3H)-quinazolinones in [MIMBES][HSO4]and [BYBES][HSO4] under three component, one-pot, microwave irradiation conditions was study, in which,1)The synthesis of 2-substituted-4(3H) -quinazolinones using 2-aminobenzoic acid as substrate, acyl chloride as C2 unit, ammonium acetate as N3 unit，it was found that the reactions completed within 6min with the yields of 87～93% in the presence of 10mol% BAILs.This synthetic method has generality for target compounds, aryl and alkyl can be introduced 2-position.BAILs could be recovered easily and recycled three times without any significant loss in catalytic activity. 2) Base on the synthesis of 2-substituted-4(3H)-quinazolinones, we using aromatic and aliphatic amine as N3 unit, successful synthesis of 2,3-disubstituted-4(3H) -quinazolinones, it was found that the yields of 74～92% was obtained within 6～8min in the presence of 10mol% BAILs.[MIMBES][HSO4] gave better results than [BYBES][HSO4]. 3) The synthesis of 3-substituted-4(3H) -quinazolinones using 2-aminobenzoic acid as substrate, ortho ester or formic acid as C2 unit, aromatic and aliphatic amine as N3 unit, it was found that the reactions completed within 4～6min with the yields of 69～94% in the presence of 5mol% BAILs. BAILs could be recovered easily and recycled three times without any significant loss in catalytic activity.