Abstract: The crack defect of nickel chrome plating layer is the main cause of the part failure. For this type of part, the most effective nondestructive test method is fluorescence penetrant inspection-hydrophilic post emulsification method. How to choose the concentration of emulsifier and emulsifier time is the key to make the hydrophilic post emulsification succeed. Through testing on standard test piece of nickel chrome plating layer under different emulsifier time and emulsifier concentration, the proper emulsifier parameters were selected to reach the detection sensitivity complying with the requirement.