Abstract: In allusion to oversized surface wrinkle at elbow pipe of products pipeline during bending, investigation and experimental analysis on bending process are carried out. Results show that startup hysteresis of hydraulic system and inappropriate design of processing technology result in oversized surface wrinkle at elbow pipe. Countermeasures taken in prestressing 2 to 3 seconds, adjusting heating power and the time to open advancing and/or cooling devices can completely solve the problem of oversized surface wrinkle at elbow pipe.