Abstract: The clarification of fermentation broth is the first link in CPC separation and purification, which has a great influence on the quality, cost and production progress of the CPC product. The present paper provides several indexes for both of the membrane filtration process evaluation and the filtrate quality assessment in the filtration process of CPC fermentation broth. Parameters influencing the evaluation indexes are discussed with a mathematic model and quantitative models have been established, thus provides a rational route for filtrate quality control and production process optimization.