Abstract: The current two-way hydraulic shock absorber has defects such as unreasonable structure design,poor seal wear resistance,poor chromium plating quality of sealing surface etc..,which often cause premature failures,even well accident.Therefore,we have conducted in-depth analysis of failure mechanism with respect of the shape parameters,sealing quality,sealing surface chrome-plating quality,internal nine thread design according to working principle of the shock absorber,main structure design,and variety of failures in the field application.It is concluded that all the failures are caused by improper use or defects in product design.According to the results of analysis,improvement measures and corresponding suggestions have been proposed in terms of the tool dimensions,seal structure and quantity,special surface treatment process and the internal thread parameters.Theoretical analysis shows that the performance of two-way hydraulic shock absorbers is greatly improved and service life are prolonged at the same time.