By using the modified extractionmethod temperature was increased from 25℃ to60℃，oscillation was extendedfrom 1 h to 2h and cation -exchange membrane method，three soil amendment application rates and three nitrogen dose combinations were set up to study their effects on sandy soil nitrogen leaching and bioavailability by combining addition of the bentonite-humic acid amendment and nitrogen in west Liaohe river plain.The results showed that，only addition of bentonite-humic acid amendment had no significant effect on maize yield and soil residual inorganicnitrogen.The combination of 20 t·hm-2 bentonite-humic acid amendment and 120 kg·hm-2 nitrogen showed the best improvement onmaize grainyield，above-ground biomass yield and soil NO 3--N residual，with an increase by 19.1% and 18.5% on maize grain yield and above-ground biomassyield，14.5% decrease on soil NO -3-N residual，respectively.However，addition of 240 kg·hm-2of nitrogen had no significant influence on maizeyield，but raised the risk of nitrogenleaching.Underthe same treatment，modified method showed little influence on soil NH 4+-N content，but increased soil NO -3-N contentcompared with standardmethod. Bentonite -humic acid amendment absorbed the NO^3--N in thesoil，it not only reduced therisk of nitrogenleaching，but also decreased soilbioavailability.It indicated that the combination of 20 t·hm -2of bentonite-humic acid amendment and 120 kg·hm-2 of nitrogen is the best combination for increasing nitrogen availability and reducingnitrogenleaching.