Yeast β-glucan has attracted much attention due to its good biological activity， but its low solubility limits its application. In order to improve the solubility of β-glucan and expand its application range， the effects of enzyme dosage， substrate concentration， temperature and time on the yield of water-soluble β-glucan were investigated. The process was optimized by response surface methodology. The functional properties and structural changes of β-glucan before and after enzymatic hydrolysis were compared. The results showed that the yield of water-soluble β-glucan was 56.12% under the conditions of enzyme dosage 4.30%， substrate mass concentration 15 mg/mL， enzymolysis temperature 45 ℃， enzymolysis time 83 min. The solubility of the product was reached 89.74%， the molecular weight was decreased to 2.99×106， 6.88×104 u and 1.40×104 u， D[4，3] was decreased from 67.49 μm to 38.25 μm， and the thermal stability was improved. The structure of β-glucan remained unchanged， which was still connected with β-1，3-glycoside bond. Circular dichroism chromatography showed that the asymmetry of water-soluble β-glucan was increased and the structure was highly ordered. Scanning electron microscope showed that the yeast β-glucan was changed from intact granules to irregular slice shape.