Selective　adsorption　of　sulfur　dioxide　(SO2)　is　an　important　clean　technology　for　purification　of　exhaust　gas　from　fossil　fuel　combustion.　The　widely　applied　zeolite-based　adsorbents　interact　with　SO2　through　weakly　physical　adsorption,　resulting　in　low　adsorption　capacity　and　selectivity　for　SO2.　Herein,　a　facile　strategy　that　combines　improving　the　textural　property　of　zeolite　and　optimizing　adsorption　sites　is　developed　for　efficient　and　stable　SO2　adsorption.　The　micro-mesoporous　silica　sphere　(MS)　with　high　specific　surface　area　and　well-defined　pore　structure　is　obtained　through　a　micelle　expander　assisted　soft-template　method,　which　can　facilitate　the　dispersion　and　exposure　of　designed　adsorption　sites-　methylated　polyethyleneimine　(mPEI).　Since　the　Lewis　basic　sites　of　N　in　mPEI　can　strongly　interact　with　the　pi-receptor　SO2,　and　the　tertiary　amine　groups　exhibit　a　weak　attraction　for　CO2,　the　optimized　MS　supported　mPEI　adsorbent　exhibits　remarkable　SO2　adsorption　performance　(7.5　mmol/g),　exceptionally　high　SO2/N2　selectivity　(16673)　and　SO2/CO2　selectivity　(551).　Moreover,　it　presents　an　outstanding　stability　in　the　adsorption-regeneration　test.　This　work　sheds　light　on　the　design　of　high-performance　organic-solid　composite　adsorbent　for　selective　capture　of　SO2.