Abstract: In order to increase the yield of crude phycobiliproteins extracted from Nostoc sphaeroides kütz, technology parameters were optimized. Through dual quadratic rotary regression orthogonal design experiment with three factors, the effects of pH value, salt concentration and extracting time on the yield of phycobiliproteins were investigated, and a mathematical model describing the relationship between the yield of phycobiliproteins and influence parameters was developed. The optimum extracting conditions are as follows: pH value 7.3, salt concentration 0.21 mol/L and extracted time 4.3 h, and the yield of phycobiliproteins is 7.125%.