Inverse fringe projection is a fast and robust optical 3D shape inspection techniqu,which is applied to online or batch inspection. A new method for generating inverse fringe is proposed,which builds the normal mapping transform relationship between projector coordinate and camera coordinate. A pixel on the projector coordinate has two suits of phase,through which its position on the camera coordinate can be located, which is called the register of projector pixels on the camera coordinate. Since the required fringe map in the camera is just simple sinusoid image, so it can easily get the inverse fringe by reading the phase of register point directly.Standard phase difference in simulation and real experiment reaches 7.044×10-6 and 3.34×10-2 separately,which gets a higher precision than former methods.Then the reason accounting for the high precision is analysed.Both simulation and experiment prove the feasibility of this method.