For the transversal and longitudinal fracture failure of diesel engine valve guide during engine bench test, the influencing factors such as material performance,  tructural stress, fretting wear, thermal deformation and assembly process were analyzed. The results show that the poor mechanical properties and the stress concentration and fretting wear caused by large assembly interference are the main reasons leading to valve transection. The assembly process of liquid nitrogen artificial pressing is the main cause of longitudinal crack for the valve guide . Accordingly, a new scheme valve guide is proposed and verified by bench test.