Abstract: Polyacrylamide solution will have a stronger hydrolysis under the condition of high temperature, then hydrolysis degree increasing, when the degree of hydrolysis exceeds a certain value, the viscosity of the solution is on the decline. If the solution of high salinity, especially with high bivalent cation content (hardness), the viscosity declines substantially, even will produce precipitation which will make polymer lose oil displacement ability. The hydrolysis degree of polyacrylamide is an important factor affecting and limiting the use of polymer in high temperature reservoirs. By studying the theory of chemical reaction dynamics, the mathematical model of the hydrolysis degree of polymer has been established theoretically, influencing factors such as temperature, salinity, polymer solution concentration on hydrolysis degree of polymer have been simulated which provided the effective guidance for polymer under high temperature and high salinity reservoir.