Abstract:A type of rotary seedling pickup mechanism used in vegetable plug seedling transplanter which can realize nonuniform continuous transmission was taken as the research object. In order to improve the working stability of the seedling pickup mechanism, the counterweights method was used to improve the structure of the seedling pickup mechanism to reduce the vibration of the mechanism and improve the performance of the mechanism. The optimization design model of the counterweight was established, and the mass and centroid radius of the counterweight was determined as 0.21kg and 102mm respectively by using the exhaustive method through UG and ADAMS software. ADAMS software was applied to carry out the dynamics simulation and analysis of the seedling pickup mechanism. Counterweight was machined and assembled on the mechanism prototype to conduct dynamics tests. The simulation and test results of bearing reaction force of the seedling pickup mechanism after addition of the counterweight were compared with that before addition of the counterweight to verify the validity of the dynamics performance improvement of the seedling pickup mechanism respectively. The prototype test results showed that the maximal amplitudes of bearing reaction force of the seedling pickup mechanism in x and y directions were reduced from 409N and 77N before improvement to 369N and 69N, respectively, which were decreased by 9.8% and 10.4%. At the same time, the variances were reduced from 5126N2 and 553N2 before improvement to 3391N2 and 398N2, respectively, which were decreased by 33.8% and 28%. The dynamics performance of the seedling pickup mechanism was better and the working stability of the mechanism was also improved.