Abstract: The application of mechanical transplanting on crops can effectively increase the product of crops and reduce the labor intense as modern cultivation techniques.But the popularization and application are limited by the problem of lower upright degree to some certain extent.A new type cam?swing link type transplanting machinewas designed to solve the problem of lower upright degree in current pot seedling planting machine.In addition, the receiving seedling stability of planting apparatus can be guaranteed well, owing to double parallel four?bar mechanism of this planting machine.In this paper, the kinematic model of the transplanting machine was established, including the equations of planting trajectory, planting velocity and planting acceleration for the planting device.For the purpose of high efficiency, interactive GUI design tool had been explored based on the MATLAB/GUI according to these mathematic equations.The influences on the transplanting trajectory of main parameters were analyzed based on MATLAB tool, including the length L₁ and original phase angle Φ1 of crank CD, the length L₂ and original phase angle Φ2 of swing AB, and the length L₅ of link AG.The system parameters which had great effects on the planting trajectory were L₁, L₂, Φ1 and Φ2.These parameters were analyzed and optimized through the method of orthogonal experiment.The experimental scheme was designed according to orthogonal table off our factors and three levels.By analyzing the range table of residual, the parameter couldbe ranged as L₂, L₁, Φ1 and Φ2 from big to small, considering the degree of significant on upright degree of seedlings.The optimal combination could be selected that L₁ is 118 mm, L₂ is 52 mm, Φ1 is 256°, and Φ2 is 316°.Under the condition of this optimal combination, the motion model of transplanting machine was reestablished to generate a new optimized planting trajectory.The top of this trajectory was smooth to benefit the receiving seedling stability of planting device.As the total height of this trajectory was about 256 mm with 190 mm higher the ridge side, the planting device couldavoid touching down seedlings planted effectively.When the planting depth reached 60 mm, the maximum residual of curve at planting seedlings parts was 0.465 mm, the mean residual was 0.253 mm, and penetration angel was 81.05°.The simulation results indicated that this optimized planting trajectory can improved the anteversion problem of seedlings that caused by compaction wheel and ensured the seedling planted higher upright degree.In order to verify the reasonability and accuracy of the theoretical model, the prototype was processed with the optimized parameters.Based on the prototype, field tests were carried out according to relevant standards in Yiyang county industrial park of China in March 2015.No crops were planted and the ridge film was mulched in the test plot before the testing, for simply obtaining test results without effects of the other crops.During the course of experiment, 30 horse?power tractor was selected as the only power.The total height of seedlings used was no more than 150 mm, and the height of seedlings substrate less than 60 mm.The plant vertical degree was considered as the main optimization indicator which influenced by the main parameter smentioned above.The data results showed that the mechanism proposed meet the requirements of pot seedling agricultural plant at the speed of 0.556 meter per second, and planting frequency was 60.7 plant percent minute.The qualified rate of upright degree with the variationco efficient of 2.03% was 95%, lodging rate was no more than 1.67%, and plant spacing error rate was only 0.22% with no lacking of seedlings.The results indicated that this machine had the good planting performances of high upright degree and low spacing error rate under the condition of high efficiency of planting.What this paper studied will provide theoretical reference for the subsequent transplanter research and development.