The present invention relates to a hatchel falling bio-pulping method, which comprises the following steps: firstly soaking the hatchel falling with hot water for 30-60min, removing the hot water, adding clean water, inoculating 3-6 percent of bacterium sporogenes at the temperature of 30-35 DEG C, and obtaining the bio-pulp of the hatchel falling by 36-50 hours; and pulping the slurry after being cleaned, and the length of the slurry is 1.5-2.5mm. After pulping, an oxygen-alkaline method is used for bleaching. The technical conditions are as follows: the oxygen pressure is 0.5-0.8MPa, the concentration of slurry is 10 to 15 percent, the temperature is 80-120 DEG C, and the time is 80-120min; and the second section adopts hydrogen peroxide for post bleaching, and the technical conditions are as follows: the use amount of hydrogen peroxide is 4-8 percent, the use amount of NaOH is 1-3 percent, the temperature is 75-100 DEG C, the time is 80-120min, and the concentration of slurry is 10 to 15 percent. The result of the bio-pulping is as follows: the yield rate is 82-90 percent. After the two sections are bleached, the KMnO4 value of the slurry is 3.0-3.5, and the whiteness is 75-80 percent of ISO.