Abstract: An algorithm called operator-splitting (OS) to solve the model of a single droplet moving in three-dimensional space was developed. At the same time, the algorithm was compared with the frequently used explicit single step Runge-Kutta (RK) algorithm. The droplet motion model in three-dimensional space was briefly introduced. The OS algorithm was showed in detail. Then the trajectories of droplets with different diameters in the wave-type plate separator were calculated numerically. In this example, the OS algorithm and the 4th order 4-step RK algorithm were both tested from the aspects of consistency, stability, numerical precision and calculating efficiency. The results show that the trajectories acquired by these two algorithms are almost the same. However, the stability and the calculating efficiency of the OS algorithm are both better than those of the RK algorithm. Therefore, the OS algorithm is a relatively stable and efficient algorithm to numerically calculate the droplet separation efficiency of wave-type plate separator.