Aiming at the problems of low efficiency of artificial operation and serious pollution during the propagation of potato tissue culture seedlings, a shear mechanism for potato tissue culture seedlings with the whole bottle transplantation was designed. The proposed mechanism can make the potato tissue culture seedlings in whole bottle which were taken from the picking seedling machinery gather, shear and import dispersion in the sub culture bottle, then get into the next generation of rapid propagation culture, and finally realize the mechanized operation of gathering seedlings and cutting seedlings process with low pollution, high efficiency and high quality. The key structural parameters of claws, cutting knife and collecting seedling funnel were determined through analysis and calculation. Taking gathering seedlings speed and cutting seedlings speed as experimental factors, the single factor experiments for analyzing the effects of gathering seedlings and cutting seedlings were carried out. The optimal gathering seedlings speed and cutting seedlings speed were determined as 3.16rad/s and 10.26rad/s, respectively. A verified test of the designed shear mechanism with the above optimal parameters was conducted. The test results showed that the qualified rate of gathering seedlings was 99.13%, the damage rate of gathering seedlings was 0.79%, the success rate of cutting seedlings was 100%, the loss rate of cutting seedlings was 1.37%, and the success rate of collecting seedlings was 97.53%. Time for completing the process of potato tissue culture seedlings in whole bottle was only 48.67s and all the test indexes met the design requirements. The designed mechanism can provide a reference for the research of potato rapid propagation robot.