Abstract: For reducing the cake moisture to a minimum level and improving working efficiency of filter press, the weight of each index is first determined by calculation of entropy of information, and the calculated results are then introduced in the TOPSIS positive-negative ideal sequence solutions. The degree of correlations of each of the 4 operating parameters of feed concentration, feeding time, pressing time and air drying time with the positive-negative ideal sequence and dewatering efficiency of filter press are determined through gray correlation analysis for defining the primary and secondary factors that exert influence on the composite dewatering indicators. As evidenced by study results, in terms of degree of influence on cake moisture, ranked first is feed time which are followed in descending order by air drying time, pressing time and feed concentration; with the respect to the effect on capacity per unit of a filter press, the above-going ranking is changed to the sequence as follows: feed concentration>air drying time>feeding time>pressing time; and as viewed from the general aspects, the most influential factor is feeding time which is followed in descending order by pressing time, air drying time and feed concentration. The research-derived achievements provide a theoretical support for the adjustment of working parameters during material dewatering process and a guidance for the optimization of dewatering process.