Simulated annealing algorithm is a mathematic model, which imitates the physical process of annealing. And optical thin film is widely used in many industry. Its design is difficult and can be regarded as an optimization problem. In this paper, we use the simulated annealing algorithm to design an edge filter, which is composed of 20 dielectric thin film layers with TiO 2 and SiO2. The simulated annealing algorithm is a very robust algorithm.© Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg 2011.