The invention discloses an automatic seedling taking and feeding mechanism used for plug seedling transplanting. The automatic seedling taking and feeding mechanism comprises a shift mechanism, a support, a sliding bar, a link mechanism, and a seedling clamping mechanism, wherein the support is arranged on the shift mechanism and used for realizing position conversion of the support between seedling taking and seedling feeding actions; and a chute and a sliding sleeve are arranged on the support, the link mechanism is connected with the sliding bar and used for driving the sliding bar to move in the chute along the track of the chute, one end of the sliding bar is inserted into the sliding sleeve and the other end of the sliding bar is connected with the seedling clamping mechanism. The shift mechanism is used for realizing conversion of the seedling clamping mechanism between the seedling taking and seedling feeding working procedure positions, and the link mechanism is used for controlling the sliding bar and the seedling clamping mechanism to rotate, so as to realize closing and opening of the seedling clamp. The automatic seedling taking and feeding mechanism is simple in structure, agile in movement, high in space utilization rate, good in seedling clamp track adjustability and strong in applicability, improves the work efficiency of the mechanism, guarantees the stable and reliable movement of the mechanism, and can guarantee good seedling taking and feeding effects aiming at different transplanting machines.