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Aiming at the Shajiang black soil tend to become hard soil blocks and there are too many large soil blocks remain on land surface after traditional tillage and rotary tillage, which seriously affects the quality of wheat sowing. A pair of roller extrusion Shajiang black soil preparation machine was designed for solving the mentioned problems. The machine can finish the series work of soil pick-up, screening and transportation, crushing and returning to the field, and flat pressing. The multifunctional material testing machine and high-speed photography were used to study the crushing mode of Shajiang black soil, and the displacement load variation law in the crushing process was obtained. The maximum crushing load was determined to be no more than 900N. Straight blade, as the key parts of the whole machine structure, its parameters such as the blade inclination angle, blade length, blade rear end height were studied. Through the force analysis of the soil block in the screening conveying device, the angle between the screen plate and the retaining plate was finally believed to be 110 degrees. By researching on the installation parameters of the crushing roller and the rotation speed of the crushing roller in the crushing device, the structure and working parameters of the crushing device were finally identified. There were three comparison through the field experiment: plow+rotary tillage+picking up and breaking (a), plow+picking up and breaking (b), plow+rotary tillage+rotary tillage (c). Comparing the results of a and c, the soil fragmentation rate of a was 89.5%, which was 44.4 percentage points higher than that of mode c. Besides, the number of soil blocks in mode b was 55.3% less than that in mode c. The mean values of standard deviation of surface roughness of mode a, b and c were 6.92, 11.58 and 17.23mm, respectively, The results showed that the surface evenness of mode a was the best, and the effect of mode b was better than that of mode c. Under certain conditions, the effect of double roller extrusion type soil preparation machine for Shajiang black soils was better than that of rotary tiller.