To satisfy the need of nanometer measurement for high accuracy optical system,the design of nanometer measurement 632.8 nm phase-shifting Fizeau interferometer is presented. The elementary configuration and measuring principle of the 632.8 nm phase-shifting Fizeau interferometer to measure concave and convex surface are introduced. Some errors that affect the accuracy of interferometer are pointed out,including phase-shifting error,geometrical configuration induced error,vibration error and errors caused by CCD,laser source and fluctuating surroundings. The magnitude of measurement errors is obtained through analysis and simulation,among which phase-shifting error,geometrical configuration induced error,vibration error and fluctuating surroundings have great influence. Finally a group of system parameters and environment paraments for 632.8 nm phase-shifting Fizeau interferometer to realize nanometer measurement are given in theory.