The planting arm of rotary transplanting mechanism for rice pot-seedling is the operation component which is used for seedling picking-up. The motion of seedling control and pushing will affect the success rate of seedling picking-up and seedling pushing directly. Aiming to solve the problems such as the long time of seedling picking-up, low success rate, no pushing device and poor pushing seedlings of the original pot-seedling transplanting mechanism, the transplanting mechanism was redesigned. The main work is to redesign cam mechanism in transplanting arms using optimization design method, decrease cam-drive angle and add the seedling pushing device. With the development of virtual prototype and physical prototype, the virtual kinematics simulation and the kinematics test with high-speed digital video camera and image processing technology were carried out. The basic consistency of the shortening time in two test was demonstrated which showed the feasibility and availability of the developed design of planting arms. The seedling picking-up tests of transplanting mechanism with different cam mechanisms as well as the transplanting mechanisms with and without seedling pushing device were developed. The success rate of seedling picking-up and seedling pushing of the developed mechanism were 94.3% and 98.6%, which were 82.9% and 88.6% higher than those of the product by original pot-seedling transplanting mechanism, respectively. It was proved that the improved mechanism can meet the requirements of rice pot-seedling transplanting.