Abstract: Monazite leaching residue is a secondary resource rich in rare earth elements, thorium, and uranium. The recovery of these valuable elements usually involves acid leaching, forming an acid-leached slurry of monazite leaching residue that contains abundant fine suspended solid particles resulting in decreased solid-liquid separation efficiency. To clarify the evolution of filter cake structural parameters during filtration, a calculation method for filter cake characteristic parameters was established based on blocking model screening and genetic algorithm optimization. Vacuum filtration experiments were conducted using 400-mesh and 500-mesh PTFE filter cloths under vacuum pressures of 20-80 kPa. By comparing the fitting performance of different blocking models for the filtrate volume-time relationship, a suitable filtration model for this system was determined, and the relationship between filter cake pressure drop and filtration time was further obtained. The genetic algorithm was then used to optimize key parameters, including the filter cake compressibility coefficient(δ) and initial permeability coefficient(k⁰). The results show that the intermediate blocking model describs the filtration process well. The optimized model achieves a Pearson correlation coefficient(PCC) above 0.96 under both filter cloth conditions. Except for the 40 kPa condition with the 500-mesh filter cloth, the coefficient of determination(R^2_2 ) is no lower than 0.92 for all operating conditions. The mean absolute error(MAE) of filtration velocity is generally on the order of 10⁻⁷ to 10⁻⁵ m/s, reaching the order of 10⁻⁵ m/s under the 400-mesh filter cloth at 80 kPa. At the same filtration time, increasing vacuum pressure enhances the filtration driving force, thereby increasing both filtrate throughput and particle deposition per unit time and consequently increasing the filter cake thickness. However, the higher pressure difference also intensifies filter cake compaction, causing pore structure contraction and a reduction in seepage channels, which in turn decreases porosity and permeability while increasing specific resistance. The compression effect is most pronounced near the filter cloth interface.