It is necessary to replenish water one by one for the mushroom sticks on the multi-layer mushroom rack during the process of mushroom production.A water injection machine for mushroom sticks on rack mainly composed of six parts including a clamping device，a water injection device，a lifting device，a rotating device，a driving device，and a positioning device was designed to solve the problems of high labor intensity，low efficiency，and inability to accurately control the amount of water injected by traditional manual water replenishment.The water injection unit is composed of a clamping device and a water injection device，the clamping and water injection for a total of 15 mushroom sticks on three layers can be completed simultaneously，and the water replenishing operation of multi-layer mushroom sticks can be realized under the driving of the lifting device.The water replenishing operation of the mushroom rack on the other side can be completed by the rotating device. According to theoretical calculation，the maximum holding force F_jmax of the clamping device is 4 750 N，and the minimum thrust F_tmin of the water injection device is 2 455 N.The rotating device needs to accelerate for 2 s before rotating at a uniform speed for 3.5 s.According to the structural design and theoretical calculation，this article developed a prototype of a water injection machine for mushroom sticks on rack，and conducted a prototype test.The results showed that the damage rate of the mushroom sticks after water replenishment was 0，with the average weight ratio of 84.8% and the average working efficiency of 230 pieces/h.The water injection machine adopts the method of replenishing water with mushroom sticks on rack，which improves the working efficiency and meets the requirements of replenishing water for mushroom sticks.It will provide a theoretical basis for the development of the water injection machine for mushroom sticks on rack.