In the middle and lower reaches of the Yangtze river,the soil is sticky and amount of rice straw is large,which will cause machine to be blocked by soil or entangled by straw.In order to solve this problem,a combined tillage machine composed of buckle plough,rotary tillage and parts for furrowing,which can cover the straw with the plough,break soil up with rotary tillage and ditch furrow with the plough at the back,was designed.According to the law of soil movement,the key parameters of plough surface including guide curve,straight element angle,tail length of plough surface,and the structural parameters including number and distance of plough were determined.Results of field test showed that traction resistance of machine increased by 23.7% and the power consumption increased by 57.2% when the working speed increased from 3.3 km/h to 4.2 km/h.Traction resistance and power consumption increased when speed increased.Due to the addition of plough,the total power consumption of machine increased by 12.3% and 20.7% compared with the rotary tillage when the speed of the machine was 3.3 km/h and 4.2 km/h under the same operating depth of rotary tillage.The machine worked better even though the power consumption was increased.Compared with the rotary tillage,the average soil crushing rate of the combined machine,the average surface flatness after tillage,the average straw coverage rate was 92.8%,11 mm,and 92.9%,respectively and increased by 2.6%,39.0%,and 22.2%,respectively.All performance parameters of the machine meet the agronomic requirements of rapeseed sowing.