a modified chelate precursor doping technique using high-purity materials and accurate gas flow control system is proposed to fabricate an efficient ytterbium-doped large-mode-area silica fibre for laser development. this technique enables to make homogeneous large-core preform with symmetrical shape, relatively low numerical aperture of approximate to 0.06 and large-core size of over 4 mm. homemade preform was drawn into standard fibre for testing and fully characterised by electron probe microanalysis and time-of-flight secondary ion mass spectrometry. on the basis of two-stage master oscillator power amplifier system, 1 kw laser output with slope efficiency of 81.0% was realised at approximate to 1064 nm.