Aiming to improve the automation level and operation performance of sugar beet harvesting machinery in China, reduce the loss of damage and leakage digging, and reduce the labor intensity of personnel, 4LT-A type traction sugar beet combine harvester and 4LTSYT-A autofollow row field simulation experiment platform were developed, and the kinematics analysis of autofollow row system was also carried out. During the tests, the 4LTSYT-A autofollow row field simulation experiment platform was placed under the beet root deviation distance detection mechanism and digging mechanism of the 4LT-A type beet combine harvester, and its power was provided by the variable frequency motor controlled by the control box. The 4LT-A type beet combine harvester was towed and powered by a John Deere 1054 tractor. Single factor bench tests were carried out by taking leakage digging rate, damage rate and response time as the autofollow row performance indexes, and taking reset spring preload force, forward speed, deviation distance, hydraulic flow and oil supply pressure and plant spacing as test factors. The significance and influence of each factor on each performance index were analyzed. The variance analysis and visual analysis of the single factor test results showed that the spring preload force, forward speed, deviation distance and hydraulic flow had significant effects on each performance index, the oil supply pressure and plant spacing had no significant effect on each performance index. With the increase of spring preloading force (range of 53~346N), the response time was increased, and the leakage digging rate and damage rate was firstly decreased and then increased. When the preloading force was 198N, the leakage digging rate and damage rate were the lowest, which were respectively 2.34% and 3.77%. With the increase of forward speed, the leakage digging rate and damage rate were increased gradually, and the response time was decreased gradually and tended to be constant. When the hydraulic flow was changed from 15L/min to 35L/min, the leakage digging rate was gradually decreased, and the response time and damage rate were first decreased and then increased. When the hydraulic flow q=25L/min, the damage rate and response time were the smallest, which were 3.77% and 0.47s, respectively. Each performance index was increased gradually with the increase of deviation distance, and the autofollow row system had a good adaptability to the deviation distance of 0~6cm. This research can provide reference for the later parameter optimization and the research of automatic row harvesting system of beet and other undersoil fruit harvesters.