A certain potato digger in poke finger’s wheel type which fit walking tractor was designed. The machine used the fenselike digging device and the separation device in poke finger’s wheel type. The structure parameters of the device for separating potato and soil was determined based on theoretical analysis.Field experimental results showed that potato digger performed smoothly in digging, lifting and transporting without any block, and potatoes were separated effectively from soil. Damage rate was 4.5%, losing rate was 3.6%, and obvious rate was 96.5%.