Abstract：In this paper,An environmental friendly lactose-biuret resin adhesive was prepared using lactose instead of formaldehyde in acid condition. The viscosity was used as an index to investigate and optimize the reactive conditions by the single factor experiment and response surface methodology（RSM）.By analyzing and comparing the experimental result,the optimum conditions of the reaction process were gained: the molar ratio of lactose and biuret was 6.03:1，the reaction temperature was 198.9℃，the reaction time was 45.3min，and the catalyst amount was 1.47%. Under these conditions，the theoretical viscosity of the products was 175.6 mPa·S and the measured values was173.8 mPa·s.