The soybean whey was pretreated in flocculation and microfiltration for recovering the whey protein.Through studying on condition of soybean whey’s flocculation and sedimentation by CaCl2,the optimal processing parameter was:pH 8.0,CaCl2 (1 mol/L ) 18 ml/L,temperature 50℃～60 ℃,lower speed agitating,flocculation time 15 min.the best condition of pressure and temperature was 0.1 MPa、40 ℃.Under the above conditions with the pretreatment,the soybean whey’ protein loss ratio was only 10.2%,the tatol sugar was hardly lost,fat was totally removed,and transmittance was also improved distinctly.