Semi-automatic sweet potato transplanters are facing the problem of artificial seedlings and low-efficient transplanting. In order to solve the problem, the automatic sweet potato transplanter with linear seedling supplying was developed. Based on multiple working procedures, this machine could complete two ridges automatically for sweet potato seedlings, furrow, plant, cover and ridge in a single time. In order to achieve the automatic seedling supply, the machine adopts the mode of the linear seedling supply transplanting. The authors analyzed the pressure resistance of sweet potato seedling and the working principle of the transplanter. Based on the analysis, the overall structure of automatic sweet potato transplanter with linear seedling supplying was determined, and the design of the key parameters of the linear seedling supply mechanism and ditching seedling planting mechanism was completed. According to the agronomic need of sweet potato ridge transplanting, the combination of soil covering and ridge repairing was carried out, which meets the requirements of soil covering and ridge repairing after ditching and planting sweet potato seedlings. Results of field experiment showed that when the transplanter was at the speed of 0.7 m/s, the average plant spacing was 151.6 mm, the qualified rate of plant spacing was 100%, the qualified rate of planting depth was 79%, the qualified rate of seeding angle was 85%, and the missing seedling rate was 2.6%. The statistics could meet the requirements of sweet potato mechanical transplanting. A mechanized carrier that adopts the new linear transplanting, this machine can provide a reference for the design of automatic mechanized sweet potato transplanting machine.