The invention discloses a method for preparing water-soluble beta-1, 3/1, 6-qlucan. The method has the steps as follow: 1) oxidization process: suspending water-insoluble beta-1, 3/1, 6-qlucan in oxidant solution at 2 to 8 DEG C, laying aside for oxidizing reaction for 16 to 24 hours for centrifugation and collection; 2) washing: stirring and washing the deposition treated from step 1) by ethyl alcohol and acetone respectively for 30mins to 1 hour for then centrifugation and collection; 3) ultrasonic process: heavy-density suspending the deposition treated from step 2) in the DMSO solution ofconcentration expressed in percentage by volume of 0.05 to 0.2 percent, and ultrasonic processing the heavy-density suspension liquid for 20 mins; and centrifugally collecting the supernatant fluid toachieve water-soluble beta-1, 3/1, 6-qlucan. Being detected, the water-soluble beta-1, 3/1, 6-qlucan prepared by the method has the yield over 95 percent and has little protein content and fat content.