The invention relates to a method and a system for olefin polymerization temperature control. The method and the system for the olefin polymerization temperature control aims at solving the problems that a polymerization reaction in the prior art is severe, temperature fluctuation is large in the process of heating and heat dissipation and bad influences on performance and quality of a polyolefin product are caused due to lag of the temperature. An artificial intelligent method is adopted. A manipulated variable of the method is the temperature. According to a designed intelligent controller, in the process of the polymerization reaction, opening time of a hot water valve, an inner cold water valve and an outer cold water valve is controlled according to deviation and slope rate of the temperature fluctuation so that accurate control of the polymerization temperature and continuously automatic control of three steps of temperature rising, temperature maintaining and temperature dropping are achieved in the process of an intermittent polymerization reaction. The invention further provides a control device for the olefin polymerization reaction. According to application, control requirements for a temperature parameter of the olefin polymerization device can be completely satisfied according to the intelligent control method, dynamic property of the system is improved and the performance and the quality of the olefin product are improved.