The invention relates to a garden transplanting seedling shading device. The garden transplanting seedling shading device comprises an insertion pole, and an upper sleeve and a lower sleeve which are mounted on the insertion pole in a sliding manner, wherein locking screws are mounted in the upper sleeve and the lower sleeve; a shading frame is fixedly mounted at the left end of the upper sleeve through a connecting arm; a balancing weight is fixedly mounted at the right end of the upper sleeve; balancing devices are uniformly arranged on the circumference of the lower sleeve; a through groove extending in the vertical direction is arranged in the shading frame; a shading net is fixedly mounted in the through groove; a left containing groove and a right containing groove which extend in the front-back direction and are provided with openings facing the through groove are arranged in a left-right symmetric manner in the left end wall and the right end wall of the through groove at the lower end of the shading net; a front sliding groove and a back sliding groove which extend in the left-right direction and are provided with openings facing the through groove are arranged in a front-back symmetric manner in the front end wall and the back end wall of the through groove at the lower end of the shading net; the front sliding groove and the back sliding groove communicate with the left containing groove and the right containing groove; a left front sliding block and a right front sliding block are respectively mounted at the left end and the right end of the front sliding groove in a sliding manner; and a left back sliding block and a right back sliding block are respectively mounted at the left end and the right end of the back sliding groove in a sliding manner.