Abstract: For the corrosion problem of synthetic hydrocarbon-recycle gas heat exchanger,the corrosion region of heat exchanger was checked by ultrasonic detection,visual and metallographic observation,and was analyzed by X-ray diffraction(XRD),scanning electron microscopy(SEM)and energy dispersive spectrometer(EDX).The results showed that the main reason of the corrosion failure was the condensation of synthesis hydrocarbon in inlet side of the pipe,where a corrosive acid environment was formed,which caused seriously local corrosion at the inlet side of the pipe.