With the popularization and development of solar greenhouse in recent years, more and more crops began to be planted in solar greenhouse. At present, in the greenhouse garden, picking tomatoes mainly relies on fruit farmers to complete manually, which not only consumes a lot of work force, but also wastes a lot of time. Taking tomato as an example, a tomato picking robot was designed which can be applied to solar greenhouse garden, patrol between greenhouse and ridge road and automatically identify ripe tomato in real time, and complete picking and collecting after identifying successful tomato. STM32 microcontroller was the main core of this design. The Mecanum wheel omni directional mobile platform was used as the mobile chassis of the robot, and the depth camera driven by Raspberry Pi 4B controller was used as the recognition device of mature tomatoes. The platform on the chassis was equipped with a wind compensation fan and a 6-DOF horizontal sliding mechanical arm. The arm was equipped with a flexible grip attached to a thin-film pressure sensor. The whole upper platform was driven by the vertical lifting structure installed on the platform under the chassis. The sliding mechanism and the lifting mechanism were equipped with ranging sensors. Through the recognition and capture of the camera driven by Raspberry Pi 4B, the coordinate data of the ripe tomato was transmitted to the STM32 controller through the serial bus. The STM32 controller drove the joint action of the mechanical arm, slide rail and lifting platform through inverse kinematics analysis of the mechanical arm, and can pick tomatoes at different heights and depths with the action of the end joint of the mechanical arm.