Aiming at the problems of high rate of leakage and damage of potato, a special sweet potato killing machine was designed. The machine was provided with traction force and working power by working tractor. During operation, the sweet potato vine was hit, knead and cut into fragments under the combined action of crushing and swinging knife, shield and fixed knife, and then thrown into the field. The machine included frame, transmission system, seedling picking device, crushing device, suspension system and other components. The machine was designed on both sides of the front end of the picking mechanism, which was composed of picking teeth, picking plate, copying plate and compression spring, which could lift and crush potato seedlings on both sides and bottom of potato ridge. The straight cutter was selected and divided into three types such as ridge top cutter, ridge side cutter and ridge bottom cutter, and reasonable arrangement was made according to the ridge shape size to realize the imitation ridge operation. The use of side transmission and  synchronous drive mode was to ensure that the crushing tool roller power was sufficient and stable. With the limited depth adjustment device, the working height could be adjusted to prevent damage to the potato block. The prototype trial production and field test were completed. The test results showed that when the forward speed of the tractor was 3.6 km/h, the qualified rate of the cutting length of the sweet potato killing machine was 92%, the planting height was 13.5 mm, the missing rate was 3.3%, and the damage rate was 0.66%, which met the requirements of use.