Based on the planetary gear mechanism which realizes the three-leaf rose line drawing method, the ratio of the number of teeth of the sun gear, the planetary gear, the internal gear, and the length of the tracing rod are deduced. The calculation formulas of the number of teeth and the length of the tracing rod for drawing rose lines of any leaf are obtained. SolidWorks is used for modeling and dynamic simulation. The simulation results show that the conclusion is correct.