At present, the vegetable transplanting machinery in China is mainly semiautomatic transplanting machines. The transplanting efficiency depends on the speed of artificial seedling pickup, its productivity can no longer meet the market, and the efficiency of twoarm rotary automatic seedling pickup mechanism also has the potential to improve. In order to realize the highspeed seedling pickup operation, it was studied to increase the number of seedling pickup arms in the case of keeping the rotation speed of the seedling pickup mechanism unchanged. A threearm rotary vegetable plug seedling pickup mechanism under the condition of satisfying the specific seedling pickup action posture was designed. Mechanical seedling pickup was used instead of artificial seedling pickup to simulate a reasonable seedling pickup trajectory. Based on Visual Basic 6.0 auxiliary analysis software was developed and a set of institutional parameters that met the requirements of seedling pickup work were obtained through humancomputer interaction. Then a threedimensional model of the seedling pickup mechanism was established and the physical prototype assembly was completed. At rotation speed of 35r/min, the seedlingpicking speed of seedling pickup mechanism was 105 plants/(min·row), the running trajectory of the mechanism was very close to the simulation trajectory through camera analysis. The picking seedling test of the Coleus blumei seedlings was carried out and the test showed that the success rate of picking seedling reached 91.2%. It was proved that the design of threearm rotary vegetable plug seedling pickup mechanism was feasible.