In order to solve the problem of uneven seedbed surface caused by the fluctuation of soil moisture content during Brassica chinensis direct seeding in the Mid-lower Yangtze River, a combined soil preparation of plowing, rotary tillage, ridging and compaction was proposed to adapt to the growth of Brassica chinensis. By combining the cultivation technology of Brassica chinensis seedbed and field tillage operation requirements, a plow-rotary and roll-forming revetment style seed bed ridging device of combined precision seeder for Brassica chinensis was designed. According to the principle of soil compaction and ridge surface forming, the dynamics of seedbed roll forming was analyzed to determine the main structure and working parameters of the ridging roll. The results showed that the qualified rate of ridge height, ridge top width and ridge spacing were 90.00%, 93.33% and 96.67%, respectively, when the operating speed of the machine was 2.0~5.0km/h. And the stability coefficient of soil firmness at the tops and sides of the double ridges were no less than 92.36% and 92.53%. The maximum difference in surface roughness of the ridge top surface was 2.19mm. The variation coefficient single row seedling number and variation coefficient of each row seeding number were both less than 10% when the device was used to achieve precision sowing of Brassica chinensis. The operating effects met the agronomic requirements of Brassica chinensis direct seeding and provided reference for Brassica chinensis sowing mechanization on ridge.