Abstract: Through the analysis of the present production situation and timber hauling to log yard in north-east forest area of China,the method "double lines with three steps" has been put forward for all round year operation.This is an approach for the study on calculation of the minimum reserve of tree length in ensuring the balanced production in log yard.Based on the statistical chart of timber hauling to yard,the paper gives methods and steps and indexes for calculating the minimum storing volume of tree length,the formulae for calculation,which is of great significance for balanced production in yard.