Three-dimensional droplet dynamics on surfaces with non-uniform wettability were investigated based on an improved lattice Boltzmann method (LBM) for multiphase flows. Both the accuracy and numerical stability were improved in this model. Droplet spreading and movement on surfaces with non-uniform wettability was analyzed. The mechanism of droplet movement and splitting under the action of wettability gradient was illustrated based on the analysis of velocity field during the droplet splitting process.