Abstract: Abstract: In recent years, the advantages of rice dry land direct seeding mulching technique have been widely approved in accumulation of effective temperature and increase of rice yield. However, the performance of the machine matched with the novel planting technology need to be further studied. A soil covering mechanism, as the key part of rice film-mulching seeder, was developed to complete the working steps of mulching plastic film, punching holes through film, seeding and covering soil. The soil coving mechanism consists of rack, screw blade, outer wall of roller, supporting shaft, curve surface soil-sampling disk and knuckle mechanic. In order to improve the mulching quality of covering soil on the film in rice dry land direct seeding, a rice field experiment (1 400 m2) was performed to investigate the effect of performance parameters of soil cover mechanism of a rice film-mulching seeder on the indices of the soil-covering at agricultural technology extension center of Raohe County, Heilongjiang Province, China. In the experiment, the working parameters and ranges were determined as follows: the tractor power in range of 24-34 kW, the working speed in range of 3-6 km/h, the diameter and the drift angle of the soil-covering disc of 336 mm and 25°-45°, respectively, the length, diameter and revolving speed of the roller of 1400 mm, 318 mm and 1.1-1.7 r/s, respectively, the soil-discharging hole dimension of 110 mm × 100 mm, the lead angle of 31°, and the hole spacing and hill spacing of 300 and 110 mm, respectively. The forward velocity of the seeder, the diameter and the drift angle of the soil-covering disc were selected as influencing factors, and the soil-covering qualification rate of seeder was selected as the objective index. Box-Behnken central composite design method was employed to establish a model to present the effects of influencing factors on the objective index. In the forward speed of 3-6 km/h, the diameter of the soil-covering disc of 300-350 mm and the dip lead angle of 25°-45°, the qualification rate of soil-covering tended to first increase and then decrease with the increase of the affecting factors, and the forward speed had the most significant effect on the qualification rate of soil-covering, followed by the drift angle of the soil-covering disc, and the diameter of the soil-covering disc was the least. The highest qualified rate was 97%, which was obtained under the optimal working condition with the forward velocity of 5.3 km/h, the soil-covering disk diameter of 336 mm and the drift angle of the soil-covering disc of 34°, with the average soil-covering thickness of 22.44 mm and the soil-covering rate of 100%. According to the requirement of 4-5 grains per hill for dry land direct seeding technology, the qualification rate of dibbling seeding achieved 93% with the seed germination rate of 99.6% and the average germination qualification rate of 87%, and the amplitude of emergence rate affected by soil-covering may be kept below 6%. Therefore, these results verified that the optimal parameters obtained by the test were reliable. This research provides technical basis for the application and promotion of rice film-mulching seeder, which greatly reduces the labor intensity of farmers and improves the working efficiency, and gives the solution for the problems of the inaccurateness of manual operation, poor evenness of soil covering, thickness being not easy to control and unsatisfactory working quality.