The directional feeding of rotary prawn peeling machine depends on manual work, which has the problems of high labor intensity and low efficiency. Feeding one by one is the premise of realizing automatic orientation of prawn. Aiming to discharge deheading prawns one by one, a prawn single separation device was designed, which was mainly composed of clamper, guide spoon, roulette, back shell and transmission mechanism. Based on the geometric dimension of deheading prawn, the structural parameters of clamper, guide spoon and other key components and the speed range of the separation device were determined by analyzing the shape characteristics and pressure conditions of deheading prawn. Single factor experiment was carried out on the experimental platform of the prawn single separation device, treating the rotation speed of the device as experimental factor, and the repeated discharge rate, leakage rate, damage rate and discharge rate of prawn as indexes. The working process of the separation device was analyzed by using image capture system. The results showed that the optimal speed of the prawn single separation device was 20r/min. At this speed, the repeated discharge rate, leakage rate, damage rate of prawn and discharge speed of prawn were 9.2%, 7.7%, 2.5% and 164 pieces/min, respectively. The structure design of the device was feasible, and it can turn disordered prawns into single output status. The design of the prawn single separation device can provide technical support for the mechanized feeding of rotary prawn peeling machine.