Abstract: To reduce the slicing time by utilizing multi-core CPU,a parallel slicing algorithm is proposed in this paper,and the properties of the algorithm is analyzed.Natural grouping feature in the model is used to build topological information groups.On the basis of this,an OpenMP-based parallel computing method is adopted to speedup construction of topological information and slicing process.A speedup close to the number of CPU cores was achieved in the test,so less slicing time was spent.The example test result shows that the algorithm proposed in this paper provides an efficient and achievable way to deal with large STL file.