Abstract: This paper analyses the internal and external factors which influence the scale of industrial clusters. The internal factors include natural resources, social resources, government support, market capacity, and external investments, while the external factors consist of capital level, diligence degree of employees, and risk preference. Based on an extended Cellular Automata model, the article designs eight simulation tests, and uses Matlab to test the influence degree of those eight factors respectively. Results of the simulation illustrate that natural resources, risk preference, capital level, and diligence degree of employees have remarkable influences on the scale of industrial clusters, while the influences of other factors are not obvious. The results also verify the existence of optimal scale of industrial clusters, and the tendency of cluster scale ascends first and descends at last, which looks like an inverse U curve.

Key words: industrial cluster, the scale of industrial clusters, Cellular Automata