An automatic measuring system to monitor the filtration and backwashing process of cross flow type ultrafiltration was developed using a personal computor. Using this system and Kaoline suspension, we discussed the backwashing effects by initial concentration, filtration cycle number, filtration time, backwashig time and backwashing pressure. Separating the cake layer from the membrane was occured in a 0.6sec at least and the change of the backwashing effect is not large with the increase of the backwashing time. Although backwashing effect decreased with the increase of filtration time and initial concentration of Kaoline suspension, and with the decrease of backwashing pressure and backwashing time, the effect of separating cake layer from the membrane is not large.
