Abstract: The paper has made a systematic theoretical analysis and test on the relation of the forest belt line amount, length, the rate of preservation and the forest belt integrality using the way of probability theory. It has advanced that pledging the integrality of the forest belt, continuous forest belt line amount relate with the rate of preservation and forest line length; On the basis of theoretical analysis,the optimum design line amount schedule of the forest belt has been set up; The theoretical basis and concreting way on the design of the forest belt line amount has been proposed.

Key words: Pretestion forest, Line amount, The way of probability theory