The invention discloses an automatic 
nutrient solution replenishing device for a multi-layer 
seedling raising rack. The automatic 
nutrient solution replenishing device comprises a support, a solution receiving box and a solution storage box, wherein the top of the support is fixedly connected with the bottom of the solution receiving box. The invention relates to the technical field of 
seedling raising racks. According to the automatic 
nutrient solution replenishing device for the multi-layer 
seedling raising rack, when a 
nutrient solution in a 
nutrient solution tray is absorbed and reduced, through the cooperation of a movable plate and a counterweight, the counterweight is pressed down to pull a pulling string, a 
piston block is separated from the bottom of the solution storage box, the 
nutrient solution enters the nutrient solution tray, it is not required that workers add the nutrient solution every day, great manpower is liberated, and time is saved. When the nutrient solution in the nutrient solution tray is reduced, a floating plate can be lowered along with the reduction of the nutrient solution, a clamping block is separated from a solution conveying 
pipe, so that the nutrient solution in the solution conveying 
pipe enters the nutrient solution tray, and seedling culture is improved; it is only required that the solution storage box is filled with the nutrient solution every day, the workers do not worry about the situation that seedling loss is caused by negligence, and the working efficiency is greatly improved.