The soil in the middle and lower reaches of the Yangtze River is sticky and hard. The quality of traditional straw returning tillage machine is not ideal, and the knife roller is easy to be twisted and the power consumption is large. To solve the above problems, a sixhead spiral straw returning cultivator’s knife roller was proposed. Secondary cutter blade was designed, and the structure of knife roller and working principle were illustrated. The reduction degree of the secondary cutter blade and the major working parameters were analyzed. The results of experiment showed that the influence of factors on power consumption and straw burial were significant, which from large to small were rotating speed of knife roller, tillage depth, working speed and tillage depth, working speed and rotating speed of knife roller, respectively. The influence of factors on straw crushing and soil pulverization were significant, which from large to small were rotating speed of knife roller, working speed and tillage depth. The optimum value of tillage depth, working speed and rotating speed of knife roller were 12.7cm, 0.7m/s and 273r/min, respectively. The results of verification experiment showed that the power consumption, rate of straw burial, rate of straw crushing and soil pulverization were 31.9kW, 93.1%, 87.5% and 78.3% when working on the optimum values. The errors between the predicted values were 4.7%, 1.4%, 1.3% and 5.8%, respectively. The results of contrast experiment showed that the power consumption and the rate of straw burial of six-head spiral straw returning cultivator were 8.8% and 2.3% lower than that of cultivator for straw returning in paddy field and dry land, respectively. However, the rate of straw crushing and soil pulverization were 3.0% and 6.1% higher than that of the latter. The research results can provide reference for the design and improvement of straw returning tillage machine in the middle and lower reaches of the Yangtze River.