In order to improve the meshing performance of harmonic gear in the transmission process, the double-circular-arc tooth profile without common tangent of the flexspline was designed, and the neutral layer curve equation of the flexspline and the accurate rotation angle relationship of the harmonic drive were established. Then, the conjugate circular spline tooth profile of the flexspline was solved based on the envelope method. Finally, the meshing characteristics of the designed tooth profile were analyzed by using MATLAB , including conjugate domain and conjugate tooth profile analysis, motion path analysis, assembly state analysis and simulation analysis. The meshing characteristics analysis results indicate that the conjugate interval of the designed tooth profiles is larger, the working arc length is longer, and the gap between tooth profiles is smaller, the number of teeth involved in meshing being larger with no interference between the tooth profiles. The meshing characteristics of the harmonic drive for the designed double-circular-arc tooth profile is good, which improves the loadbearing capacity and transmission accuracy of the harmonic drive and reduces the noise in the transmission process, thereby improving the performance of the harmonic drive.