A seedling picking and chain breaking device for a chain paper pot seedling transplanter was designed with conventional hexagonal cross-section chain pot seedlings to solve the problems of continuous chain transplanting with unadjustable spacing of plant and inability to meet the requirements of transplanting crops with large spacing of plant in the existing chain paper pot seedling transplanters. The structure of key components and the range of working parameters were determined through theoretical analyses of the working process based on explaining the working principle of the seedling picking and chain breaking device. An experiment bench was set up for the experiment with single factor. The orthogonal combination experiment of three factors including the opening of the pinch finger， the inclination angle of the seedling chute and the planting frequency and three levels with the success rate of seedling taking and the rate of matrix loss as the evaluation indexes was conducted to analyze and optimize the effect of each factor on the evaluation index. The results showed that the effect was better when the opening of the pinch finger was 52 mm， the inclination angle of the seedling chute was 20°， and the planting frequency was 45 plants/min. The success rate of seedling taking and the rate of matrix loss in the bench experiment and the soil trough verification experiment was 91.3% and 14.2%， and 87.5% and 17.4% under this combination of parameters. It will provide reference for the development of the whole chain pot seedling transplanter.