Determining the optimal rotational felling period, for both natural and artificial forests, was and still is one of the most important problem in forest management. But the questions such as how to determine it, what principles to base on, or what models to use, etc. are still problems.In this paper, the author tried to explore the principles, acording to which the optimal rotational felling period can be determined. Here five basic principles-productive, economic, ecological, social and systematic-were proposed.Since the function of forest is multi-effect, not single, so generally speaking, the rotational felling period is a multiobjective programme:According to this general model, different mathematical models can be deduced from different streesed point.Finally, some simple mathematical models were discussed.