The invention discloses a method for manufacturing a polysilicon resistor in CMOS technology. The method comprises the following steps that a gate medium layer and a polysilicon layer sequentially form; phtoetching is carried out and simultaneously a polysilicon gate and a polysilicon resistor form; an injection area for injection of an N-type source drain is defined; the area simultaneously includes a area where the polysilicon resistor forms; N-type source drain injection is carried out, and simultaneously, N-type impurities are injected into the polysilicon resistor; an injection area for injection of a P-type source drain is defined; the area simultaneously includes an area where the polysilicon resistor forms; P-type source drain injection is carried out, and simultaneously, P-type impurities are injected into the polysilicon resistor; and rapid thermal annealing is conducted to realize impurity activation. The method of the invention can lower cost.