Expression difference of heterologous recombinant protein in Pichia pastoris with different specific growth rate (mu) was observed. The expression conditions of recombinant human interferon omega (rhIFN(omega)) in logarithm phrase Pichia pastoris with higher mu were optimized by shake flask tests under various initial pH, methanol concentration, duration of the induction, cell density, and medium volume. The results showed that there were prominent influences of mu on expression of rhlFN(omega). The maximum yield of rhIFN(omega) in the Pichia pastoris with mu of 0.1612 h(-1) was 558 mg/L. However, these in the Pichia pastoris with mu of 0.1321, 0.0505 and 0.0052 h(-1) were reduced by 50%, 68% and 99%, respectively. In 250 mL shake flask, the optimal medium volume, cell density, initial pH, methanol concentration, frequency and duration of methanol induction were 30 mL, 200 - 300 g/L (WCW), natural, 15 g/L, 1 time in every 24h and 4d, respectively. Under the optimal expression condition, the maximum yield of rhIFN(omega) in logarithm phrase Pichia pastoris was 1070 mg/L which was increased by 149% more than that under the initial condition.