Abstract: In this paper,the influence of the operating conditions (concentration,pressure and temperature) on separation of polysaceharide of agaricus blazei murril by ultraflltration membranes was quantitatively studied and the corresponding mathematical equation was also found by using a linear multi-regression model on the basis of the standarded factors.The results showed that:1) For membrane flux,the pressure, concentration and temperature were all the obvious influence factors,and the pressure and temperature played a positive role in the flux,but the concentration played a negative contribution.The influence degrees of concentration, pressure and temperature on the flux were orderly concentration (78.3%), pressure (16.61%),temperature (5.09%);2) For the membrane retention,both the operating pressure and concentration were the remarkable influence factors and the temperature was only an influence factor,but was not an evident influence factor.The pressure and temperature played a negative role in the retention and the concentration played a positive contribution, and the influence degrees of concentration, pressure and temperature on the retention were orderly pressure (47.35%),concentration (42.7%),temperature (9.95%);3) The quantitative relationships between membrane flux or membrane retention and operating conditions (pressure,concentration and temperature) were also obtained,respectively.