Thickness variation of particleboard is one of the urgent problems which needs to be solved in the wood-based panel industry of China. In this paper, the factors of thickness variation control in a typical particleboard plant are studied by means of statistical analysis. The results are given as follows: the level of thcikness variation control is much lower than advanced world level; the thickness variation affected by mixed species as raw materials accounts for about 55% of total square deviation, and the others are affected by forruing unit and hot press; the correlation of thickness with weight of the boards is significant, and the weight fluctuation of the mat in length and width doesn′t come up to the required standards. Further more, a recommendations on controlling the thickness variation of particleboard are put forward