Abstract: Addressing the new manufacturing process flow for the J55 oil well weld pipe,a testing platform for the cooling process is designed and set up,which aims at studying effects on the microstructure and mechani-cal properties of the steel pipe by related cooling elements,including cooling rate,heating rate and spraying type,etc.The testing result demonstrates that accelerating the cooling rate after hot-stretch reducing will benefit improvement of mechanical properties of the pipe,and the same purpose will be also met by means of inceasing the reheating rate prior to hot-stretch reducing,and that spray-cooling with the tangent circular jet will greatly improve cooling uniformity of the pipe.