Objective: To optimize bio-solid bidirectional fermentation conditions of Trametes robiniophia for Isatidis Radix and determine fermentation terminal. Method: Dependent variable was the content of polysaccharides

while independent variables were temperature

moisture and inoculation amount

response surface methodology was used to optimize bio-solid bidirectional fermentation conditions;Then fermentation terminal was defined.The content of polysaccharides was determined by UV. Result: Optimal fermentation conditions was as following:temperature 29.4 ℃

moisture 75.5%

inoculation amount 0.826 mL·g-1

bias between the observed value(11.496%) and the predicted value(11.548%) of the content of polysaccharide was 0.45%

regression coefficients of binomial fitting complex model was as high as 0.982 6;Terminal of bio-solid fermentation was 20 d. Conclusion: Response surface methodology could be used to optimize bio-solid fermentation conditions of T. robiniophia for Isatidis Radix with good prediction.