In order to solve the problems of small size of seedling picking jaws of automatic vegetable pot transplanting machine, the structure and installation method of picking force detection sensor interferes with the normal picking action of picking jaws and affects its accuracy and service life, selecting polydimethylsiloxane (PDMS) film as the dielectric layer of sensor and a built-in pot picking force sensor was developed. The PDMS film was selected as the dielectric layer of the sensor, and a built-in potting force sensor was developed. Firstly, a simulation model of cavity, pot substrate and seedling jaw was established, and LS-PrePost software was applied to simulate the coupling of seedling extraction process, obtain the maximum force area in the contact area between seedling jaw and pot substrate, and determine the structure and size of seedling jaw and sensor;the clamping force signal detection system was designed, and the hardware circuit and acquisition software were combined to complete the capacitance-voltage conversion, signal amplification, noise filtering, and realize the acquisition of clamping force signal. In order to realize the functions of acquisition, processing, display and storage of the gripping force signal, the system was designed. In order to verify the performance of the sensor, calibration test and indoor validation test were conducted;the calibration test showed that the average sensitivity of the clamping force sensor was 0.3728N/V, the average linear coefficient of determination was 0.9892, the accuracy was 7.548%, and the range was 7N, which satisfied the accuracy requirement of clamping force detection in the transplanting process;the indoor validation test showed that the clamping force detection sensor had good stability and adaptability, and can be used for real-time and accurate detection of the clamping of transplanting machine pick-up mechanism.