The parameters of paddy field straw reuse and leveling machine, such as the rotating angle of leveling board, the force and placement angle of the ascend cylinder, were optimized in design. The machine integrated the function of rotary tilling, breaking soil, cutting straw, burying straw and leveling soil. It is applied to leveling soil and returning straw to field in paddy field mechanized harvest, and it has many merits such as small working resistance, good burying straw, and leveling soil effect etc. Experiment shows that it can directly return straw such as rice straw, wheat straw, and high stubble to field in one time. It has strong ability to carry soil and slurry with no interference. It ascends freely, and acts to respond quickly. It integrates three processes such as cutting straw, breaking soil and leveling soil, which is an efficient technology to return straw in paddy field.