The quadratic orthogonal rotation design with five factors was used to study the effect of acid concentration, the ratio of liquid to solid, time, temperature and extracting times on the yield of polysaccharides by acid extraction from rapeseed meal. Functional models of yield to five factors were established by RSREG software in SAS8.0. Results show that the regression equation is significant, and the mathematical model for the simulation is presented; the effect order of five factors on yield is as follows: temperature>extracting times>time>the ratio of liquid to solid>acid concentration. The optimum technical conditions are as follows: rapeseed meal is marinated with 18～22 times of 0.10～0.14 mol/L HCl at 100℃ for 1.4～1.8 h, extracting times are 4～5. The yield of soluble polysaccharides by acid extraction from rapeseed meal is over 3.1% under these conditions.