In order to solve the problem of dust pollution caused by centrifugal or airflow jet quicklime spreader in paddy fields, a quicklime spreading mechanism of swing-tube type was designed and installed on the rotary tiller, which was mainly composed of bins, spiral feeding device, oscillation device, and the transmission system. Taking the variation coefficient of uniformity as the evaluation index, the optimal parameters of the mechanism were revealed by test on single factor such as machine moving speed, dip angle and frequency of the swing tube as well as the analysis of response surface. The results show that the frequency of swing tube takes the priority in effecting the uniformity of lime spreading volume, as followed by the machine moving speed, and the dip angle of swing tube. When the frequency of swing tube is 3 Hz with 45° dip angle of swing tube and the machine moving speed of 0.97 m/s, the variation coefficient for horizontal and vertical uniformity is 9.1 % and 13.9%, respectively, which can meet the requirements for quicklime spreading.