In the wheat-maize rotation area of North China Plain, it is widely recognized that there are some problems in the wheat broadcast sowing under the condition of the maize straw mulching, such as straw blockage and wheat seeds planted on the maize straw. In order to solve these problems, taking advantage of the soil-thrown model of down-cut rotation tillage to form soil and straw sequential cover, a straw post-covering wheat planter was designed, which could implement the following function at one time: rotary tillage, uniform-broadcast sowing, anti-blocking, covering soil and straw and compacting. The planter included the following nine parts: suspension frame, gearbox, rotary tillage device, soil-oriented plate, seed-dividing device, soil-straw separation device, multifunctional ground wheel, frame, seeding device, and so on. The layout of rotary blades was symmetrical helix arrangement, and the maximum height of the thrown granule was calculated as 0.52m, the maximum displace in the horizontal direction was 0.79m, and the position parameters of the soil-oriented plate were determined. By means of the performance test, it was preferable that the distance between the seeding-dividing device and the horizontal direction was 35° and the distance between the seed-dividing plates was 50mm. The planter field experiment was conducted in Zhuozhou Experimental Station of Hebei Province, China. And the results indicated that the down-cut rotary tiller could effectively throw the soil and straw and avoid maize straw blockage. The depth of tillage was around 148~152mm, the stability coefficient of tillage depth was 95.5%, slip rate of multi-function walking wheel was about 5.3%, the passing ability of the planter was good and the performance can meet national standards;the weights of maize straw was 1.07kg/m2 after sowing, which can reach 80% of straw amount before sowing;the depth of sowing was around 30~35mm, sowing pass rate was 91.1%, the mean number of wheat seeds in the rectangular frame of 10cm×25cm in different positions was around 29~30, which met the agronomic requirements.