Experimental investigation of the microfiltration (MF) using a revolving cross-flow membrane filter was performed under the condition of constant pressure difference, and different flat membranes made of polyvinylidene fluoride (PVDF, 0.1 mu m), cellulose acetate (CA, 0.22 mu m), sulfonated polyethersulfone (SPES, 0.22 mu m) and polyamide (PA, 0.45 mu m), respectively, were used in filtration experiments. The dependence of the filtrate mass of the cross-flow MF on time was measured on-line. The experimental results showed that the effect of the cross-flow on high viscosity medium was more significant than that on the low viscosity one.