One of the most important decisions that a forest owner must make is to determine whether a forest stand should be cut or reserved, or when it should be cut in accordance with the estimation of its financial maturity period with the maximization of the total net present value of the whole forestry stand. In this paper, we deal with multistage serial decision making models and we can apply the multistage linear programming method to these problems. This paper deals with a network planning model of silvicultural investment at first, and then discusses how to apply this network planning model, multistage linear programming methods and some applications for deciding the financial maturity period of the individual forest stands. This planning model can provide effective information for deciding the financial maturity period and maximization of the net present value of entire forestry stands under the upper limitations of labor utilization and cutting area and the lower limitation of the forest stands area. According to this planning method, we can predict the long term treatment of forest stands more than 30 years in to the future. This planning model can therefore furnish more effective information on the long term forest management decision making of private forest owners.