On the basis of the multi-segment function construction method, the reproduction design of non-circular gear pairs with preset time-varying transmission ratio is proposed. Combined with the practical application of non-circular gear pairs in industry, a new continuously variable transmission mechanism with non-circular gear pair is presented. The influence of basic parameters of non-circular gear on output transmission ratio is discussed. By using software, such as SolidWorks and Adams, the simulation model of this continuously variable transmission mechanism is established. The simulation results show that a variable output speed ratio can be obtained by changing the relative phase angle of non-circular gear pair, and the influence of the relative phase angle on the output speed ratio is revealed. A non-circular gear pair experimental platform is built, and the experimental results show that the change trend of the experimental transmission ratio is consistent with that of the theoretical transmission ratio, with the maximum experimental error of 6.8%, demonstrating the feasibility and correctness of the theoretical analysis of this variable transmission mechanism.