To improve the automation and efficiency of plug seedling transplanter, a full-row-pick-up and single-dropping seedling transplanter was designed based on the type-PVHR2 semi-automatic transplanter with rotary seedling-received cup device. The seedling pick-up end-effector system performed the removal of total number of seedlings in a row and dropped them individually into their cups. The rotary-lifting mechanism was used to help the end-effector to move down to pick the seedlings from the tray upwards, rotate at 90°to drop the seedlings into the cups, and reverse at 90° to the upside of tray. With the principle of fully picking the row seedlings and dropping them one-by-one in mind, seedling pick-up unit driven cam contours were designed to open and close the pick-up units. Based on the transplanting requirements, motion matching and timing control of the mechanism and the cams were carried out to ensure proper coordination in the transplanter. Automatic transplanting experiments for the 72-hole plug cucumber seedlings with the age of 28d showed that the designed mechanism was reliable with a success pick-up rate of 95% at pick-up speed of 3600 seedlings/h, pick-up embedded depth of 27mm, and pick-up angle of 10°.