Abstract: Based on the difference of temperature needed for strain growth and enzymic catalytic reaction, the process of biological degumming using Bacillus subtilis was divided into two stages for good retting efficiency. The degumming conditions were optimized as follows: the amount of K2HPO4， 0.8%; the proportion between bast and water, 1:25; the inoculation amount, 0.5%; and under such conditions, degumming was carried out at 37 ℃ for 18 hours, and then raised the temperature to 45℃ and held for 0.5 hours. Good degumming result was obtained by this process with the residual gum content of 10.84%, which was decreased by 4.95% when ompared with that without raising the temperature in the latter stage.