The hydrostatic test for Class 1 components in the phases of manufacturing and installations is a critical pre-requirement for subsequent commissioning and secure operations. The discrepancies of the requirements for hydrostatic testing are compared and analyzed between the different versions of French standard of Design and Construction Rules for Mechanical Components of PWR Nuclear Islands （RCC-M）. Taking account of the characteristics of the system and structure of CPR1000 and EPR reactors, the differences of test pressure and test boundaries of hydrostatic test for Class 1 components in the manufacture and the installation phases are presented. The method on how to select test pressure for EPR Class 1 components in the manufacture and the installation phases is also explored and discussed. The conclusions can provide important reference for hydrostatic tests for EPR reactors.