Series design of transplanting parts of vegetable transplanter was achieved by the digital design based on UG and VB.NET. First of all, mathematical model of rotary ordered transplanter was established. 3-D model of parts and virtual assembly of transplanting device were completed with UG software. By means of VB.NET and secondary development tools UGOPEN in UG, special custom menu items were added in UG software; the user could input or change relevant parameters based on agronomic requirements of different vegetables, then 3-D model of the corresponding mechanism was automatically generated to achieve digital variant design of transplanting device. The results showed that this digital design method shortened design cycle and improved design efficiency. 