In order to realize high-efficiency and low energy-consumption mechanized ploughing operation in the large-scale planting area of Astragalus smicus green manure, based on the structure placement idea of front-end buried-cutting and back-end overturning, an incisal-burying and ploughing combined machine with no power input for Astragalus smicus green manure in its flourishing period was designed. The biological characteristics and pressure-shear strength test of Astragalus smicus in full-bloom stage were studied, and then the key components such as roller components, front suspension connection components and grid-type plough were designed. Through theoretical calculation and mechanical analysis, the radius of press-cutting roller for smooth incisal-burying of Astragalus smicus stalks was 305mm, and the sliding cutting angle was ranged from 34.3° to 55.7°, the grid-type plough surface was designed by using the horizontal straight element method, the parabolic equation of the guide curve was derived and the influence regularity of plough element-line angle was drawn as well. The results of field overturning test of Astragalus smicus green manure in full-bloom stage showed that with the operation speed of 5.8~6.0km/h, the qualified rate of stem-cutting length was 92%, the stability variation coefficient of tillage width was 3.7%, the stability variation coefficient of tillage depth was 5.6%, the rate of soil fragmentation was 85.6%, and the rate of vegetation overturning coverage was 98.3%, the test indexes met the requirements of national and industrial standards. The designed incisal-burying and ploughing combined machine can work efficiently up to 0.67~1.20hm2/h, which was obviously superior to the conventional overturning modes such as animal plough, mouldboard plough and rotary tiller in terms of overturning quality and the combination pattern, and had good popularization and application value.