The invention discloses a self-adaption bit 
distribution method based on 
code rate control of a hierarchical B frame structure. The self-adaption bit 
distribution method comprises the steps of: 1, figuring out a target bit number distributed to each GOP (Ground Observation Post) on the basis of the length requirement of a 
video sequence and the GOP in a configuration file attached by the 
video sequence and the speed requirement of the target bit; 2, figuring a target bit number distributed to each time layer in the hierarchical B frame structure on the basis of the target bit number of each GOP, obtained in the step 1; 3, figuring out a target bit number distributed to each 
image frame in the same time layer on the basis of the target bit number of each time layer, obtained in the step 2; and 4, updating a 
weight value of each time layer through iteration calculation according to coding information of a coding image. On the premise of no increase of the bit numbers consumed by the video coding actually, the coding complexity of each 
image frame in the 
video sequence is accurately predicted, each time layer bit distribution 
weight value in the hierarchical B frame structure is updated through iteration calculation, and the target bit numbers are distributed for each frame of image reasonably, thus coding efficiency of the video sequence and decoding quality of each frame of image are increased.