Abstract: This paper analyzes the reasons for the three cracking of bundles and tube sheets in the cycle oil slurry steam generator in SINOPEC Cangzhou Company.It is found out that the unplanned downtime of the unit,the recovery process and the pump failure resulted in the abnormal fluctuation of the oil slurry flow and the temperature which led to stress corrosion cracking of the tube sheet.The paper then brings forward corresponding countermeasures from such aspects as optimizing production operation,revamping equipment and so on.