The lipase r27RCL from Rhizopus chinensis CCTCC M201021 was heterologously expressed in Pichia pastoris GS115 by simultaneous co-expression with two secretion factors ERO1p and PDI involved in the endoplasmic reticulum (ER). Compared to the expression of the lipase alone (12,500 U/ml), co-expression with these two proteins resulted in the production of larger total quantities of enzymes. The largest increase was seen when the combined ERO1p/PDI system was co-expressed, resulting in approximately 30 % higher enzyme yields (16,200 U/ml) than in the absence of co-expressed secretion factors. The extracellular protein concentration of the recombinant strain Co XY RCL-5 reached 9.39 g/l in the 7-l fermentor. Simultaneously, the fermentation time was also shortened by about 8 h compared to that of the control. The substrate-specific consumption rate (Qs) and the product-specific production rate (Qp) were both investigated in this research. In conclusion, the space-time yield was improved by co-expression with ERO1p and PDI. This is a potential strategy for high level expression of other heterologous proteins in P. pastoris.