The effects of the end face angle on the full flow of the low pressure safety valve were studied by CFD calculation and test.The results show that the full flow is large when the low pressure safety valve is installed with the No.1 spool (the end face angle is 30°).The full flow of the low pressure safety valve is too small when it is installs with the No.2 spool (the end face angle is 15°).The flow field analysis shows that in the same opening of the spool,the full flow of low pressure safety valve installed with No.2 spool reduces by 10% compared to that installed with valve No.1 spool.