The four kinds of the structure characteristics of rotary type interferometer are mainly analyzed from the classical Michelson interferometer structure in the paper. The Optical path difference between the interferometer and the rotation angle is also analyzed. By setting parameters, the four kinds of rotary type optical path difference of the interferometer are simulated based on the optical path difference formula. The rotation velcocity of the four kinds of interferometers is also simulated. By simulation and contrast of the optical path difference, the relationship is intuitively reflect by figure between the optical path difference and the rotation angle. The scope of the rotation angle is discussed within 3% of the velocity errors. It is the very good reference significance to study the structure and properties of the interferometer by analyzing and simulating the optical path difference discussed in the paper.