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Ultrasonic and electric field were introduced into pumpkin polysaccharide ultrafiltration independently or simultaneously.Parameters of ultrasonic including ultrasonic power,frequency as well as temperature and pressure during ultrafiltration were investigated by inspecting their effects on permeation flux or rejection rate Then,effects of electric field including electric intensity and pulse frequency were investigated in the same way.At last,effects of complex fields were studied.The results indicated that: (1)both the introduction ultrasonic and electric field could enhance ultrafiltration efficiency; (2)There were peak values of the enhancement of electric field,when electric intensity exceeded 625V/cm or pulse frequency exceeded 600Hz,ultrafiltration efficiency decreased; (3)A cooperation effect was observed when the complex field was introduced; (4)introducing physical fields contributed to reduction of ultrafiltration membrane contamination and recovery of permeation flux with following sequence: 8kHz ultrasonic +625V/cm electric field >40kHz ultrasonic +625V/cm electric field >625V/cm electric field >28kHz ultrasonic >650V/cm electric field >40kHz ultrasonic.