superhydrophilic antireflective periodic mesoporous organosilica (pmo) coating was prepared on flexible polyimide substrate via solvent evaporation-induced self-assembly (seism method, in which tetraethoxysilane (teos) and a special bridged silsesquioxane were used as reactants. the bridged silsesquioxane, eg-bsq was synthesized through the stoichiometric reaction between 3-glycidoxyporpyltrimethoxysilane (gptms) and ethylene diamine (eda). under the influence of surfactant, teos and eg-bsq co-condensed and enclosed the ordered mesporous in the coating. the results of grazing-incidence small-angle x-ray scattering (gisaxs) and the transmission electron microscope (tem) indicated that the mesopores belonged to a fmmm orthorhombic symmetry structure. with increasing eg-bsq concentration, the mesoporous structure in the pmo coating becomes more and more disordered because silica mesopore walls shrunk or collapsed during calcination and consequently the refractive index of pmo coating became larger. the antireflective (ar) pmo coating showed an optical transmittance of 99.54% on polyimide (pi) much higher than the 88.68% of bare pi. the water contact angle of pmo coating was less than 9.0, which indicated the ar pmo coating was superhydrophilic. moreover, the pmo coating showed an excellent mechanical property, the transmittance of the pmo coating displayed a very low loss of 0.1% after abrasion of 25 cycles by cs-10f wearaser.