With JC2000A Contact Angle Measuring Apparatus and established model of rice straw surface wetting, to improve the surface wetting properties of Rice Straw, effects of four kinds of alkali spray on Rice Straw at room temperature on contact angle was studied. The result shows that after alkali treatment the surface wettability of Rice Straw obtained significant improvement, contact angle decreases with the treatment time extended. The contact angle change rate reached the largest within 10min with the decreasing gradient of 20.64% when rice straw was dealt with NaNH2 at the mass fraction of 1%. Under the same conditions, rice straw processing with CaH2 has the minimum gradient contact angle change rate of 3.6%, A large number of Ca(OH)2 formation made The contact angle did not change significantly with time extended. Effect of NaOH treatment changed significantly over time, the optimum conditions of processing technology were obtained through orthogonal test: concentration of NaOH is 0.6%,solvent ratio 1:3.5 and reaction time 12h.