Abstract: Preparation of apple pomace soluble dietary fiber by water bath and ultrasound and its properties from apple pomace as raw material were studied.The technical parameters of water bath and ultrasound extraction were as follows respectively :water-bath temperature 80℃, water-bath pH5, solid-liquid ratio of water-bath 1∶20g/mL and water-bath time 90min.Under these optimal conditions the SDF yield was 12.76%;ultrasonic temperature 60℃, ultrasonic pH5, solid-liquid ratio of ultrasound 1∶20g/mL, ultrasonic time 45min and ultrasonic power 225W.Under the optimal conditions, the SDF yield was 14.14%.The ultrasonic method could accelerate the organization hydrolysis of apple pomace, which was proved by SEM analysis.At the same concentration the antioxidant activity of apple pomace SDF was better than that of apple pomace, but lower than the commercial synthetic antioxidant (BHA) .