Abstract: The mathematical relationship between the operational perfor mances (filtering precision and efficiency) of P/M filter materials and the properties of raw material powder(particle size and size distribution) and technological parameters(sintering temperature)is deduced mathematically and discussed on the base of experiments, when spherical powder is used as raw material for sintering loose powder materials, an equation can be set up to describe the relation between pore sizes in a freely stacking powder body and the diameters of the particles. Hence, a function between the filtering precision of the filter and the particle size of the original powder can be deduced. The data obtained from sintering experiments and the structural analyses of sintering bodies can be treated by a microcomputer, and math-models dealing with filtering efficiency, particle size distribution and sintering temperature can be established. They can be used for the selection of original powder with suitable properties and the determination of the optimum sintering parameters in practical production. It will speed the research work, raise the productivity and improve the quality of the products. It has been proved successfully by auther's research work and practical production. Under certain conditions, the math-models have been used in the manufactures of flame barrier and image plate materials, helping to choose the maximum pore diameter and critical fire-extinction diameter of the materials.