An important factor for the stability of air floating guide rail with high operating accuracy and stability is that the gas has error averaging effect.In order to study the error averaging effect,through multiple different wavelength of the sine function,the guide rail profile error was simulated,and the physical model of the plane air floating was establish.MatLab and finite difference numerical method were used to calculate the equilibrium position parameters of the air floating guide rail in motion process,and the least tolerance method was used to calculate the operation straightness of air floating guide rail.The results show that a obvious error averaging effect is found for air floating guide rail by gas lubrication.Compared with no gas lubrication,the operation straightness of air floating guide in the ventilation state is improved by about one times,the profile error is improved by about 2/3 compared with that of static guide rail.The established calculation method of gas error averaging effect provides a theoretical basis for the study on all influential factors of error averaging effect.