Abstract: This paper mainly studies the relationships between biomass/activity of cellulase/yield of etnanol and the changes of substrate humidity during the solid-state cultivation for ethanol production with corn stover by Trichoderma koningii TR6 and saccharomyces cerevisiae CB2. The result indicates the inconsistence of optimum substrate humidity for producing cellulase with that for producing ethanol. The result of this experiment shows the substrate humidity is most influenced by fermenting temperature, less influenced by aeration, and least influenced by carbon dioxide producing rate(CPR).