In view of the problems of high labor intensity and high operation cost caused by the manually laying trays one by one in the field, a symmetrical arrangement of combination double cams controlled automatic tray laying mechanism was presented. The working principle of this mechanism was analyzed, to realize four actions of tray, chuck, separation and reset of stacked rice trays in order, and finally achieve the laying effect one by one in order. The parameter calculation model of the mechanism was established, and the auxiliary analysis and design software was written, and a set of optimal mechanism parameters were optimized as follows: base circle radius of the two cams were 15mm and 16mm, key length parameters were as follows: the extended length of the claw was 15mm, the width of the plate was 40mm, and the cam rotation center distance from the sheet metal shell wall was 30mm. The prototype was developed and the orthogonal experiment design method was used for experimental research. It was found that when the motor speed of the laying mechanism was 600r/min, totally 10 trays were put into the rice tray box in each pile, the trays were laid at a height of about 100mm from the ground, the passing rate of the total trays reached 97.16%, and the efficiency of the trays laying was 360 trays per hour. The mechanism can be loaded into the field automatic tray-laying equipment to replace manual plate-laying one by one and reduce the intensity of manual tray-laying. It can also be integrated into the seeding line as an automatic tray feed device.