The invention provides a manufacturing method of a polysilicon high-resistance device. The manufacturing method relates to the technical field of semiconductors, and comprises the steps of: providing a semiconductor substrate which comprises a PMOS region, an NMOS region and a polysilicon high-resistance region, and forming a patterned polysilicon resistive layer on a semiconductor substrate in the polysilicon high-resistance region; and performing N-type ion implantation on a region where a source/drain region is formed inside the NMOS region and the polysilicon resistive layer simultaneously, and performing P-type ion implantation on a predetermined region where a source/drain region is formed inside the PMOS region and the polysilicon resistive layer simultaneously, wherein the implantation dose of N-type ion implantation and that of the P-type ion implantation are different, and a high-resistance region of the patterned polysilicon resistive layer is formed through neutralizing and doping of P-type ions and N-type ions. According to the manufacturing method, Ntype and P-type impurities are implanted into the same polysilicon resistive layer when performing highly-doped implantation in the source and drain regions, so that the two impurities are mutually neutralized, the purpose of reaching high resistance with low net doping concentration is achieved, the cost is saved, and the process is simplified.