[Background] Straw mushroom (Volvariella volvacea) is one of the most varieties of edible fungi with Chinese characteristics, and its consumption increased year by year, the potential industrial development for V. volvacea is tremendous. Liquid spawn used in straw mushroom cultivation is the development trend of factory production, the current research in liquid spawn of straw mushroom are mainly focus on the optimized formula and growth condition, however, less research was done on the mycelial activity during the cultivation process. [Objective] Study the physiological changes of straw mushroom in liquid spawn cultivation, and analyze the cultivation end-point. [Methods] Since cultivation 48 h, collection samples every 12 h, the biomass and protein content of mycelia were measured in 168 h. Moreover, pH value, sugar degree, reducing sugar contents, cellulase, hemicellulase and laccase activities of liquid spawn filtrate were determinated and analyzed in the cultivation process. [Results] The results showed that after 84 h of cultivation, the growth rate of mycelia diminishing and the biomass increased slowly, the pH value, sugar degree and reducing sugar contents reduced gradually, cellulase and hemicellulase activities also declined gradually. After 96 h, the protein content of mycelia declined while protein content of filtrate rised obviously. [Conclusion] The research on physiological changes of 9715 liquid spawn indicated that 84?96 h was the cultivation end-point, and the results can provide important reference value for liquid spawn application in the straw mushroom 9715 factory production.