In order to solve the problems of great impact and vibration and poor dynamic performance of incomplete non-circular gear transmission applied in the rotary transplanting mechanism for dryland and rice plug seedlings, the analytic method was used to carry out improvement design for the buffer device of incomplete non-circular gear mechanism. The kinematics and force analysis of the buffer device were completed, and an analysis and design software based on VB platform for the buffer device was developed. The structure design of the buffer device was carried out. The dynamic performance of the transplanting mechanism with the improved buffer device was studied through theoretical analysis. The dynamic test bench of the transplanting mechanism was built and the dynamic tests were conducted for the transplanting mechanism installed with buffer device before improvement and postimprovement respectively. The dynamic test results showed that the maximum amplitudes of bearing force of the transplanting mechanism in X and Y directions were reduced from 365.5N and 48.4N before improvement to 345.2N and 42.2N after improvement, which were decreased by 5.55% and 12.81%, respectively, while the variances were reduced from 4880.3 and 148.7 to 4516.1 and 126.1, which were decreased by 7.46% and 15.20%, respectively. The test results after improvement were consistent with the corresponding results of theoretical analysis. The improved design of the buffer device was correct and effective, and the dynamic performance of the transplanting mechanism was improved.