The invention discloses a flexible wall protecting device of a hydraulic support and a coal wall supporting technological process. The main structure of the flexible wall protecting device comprises aflexible gasbag, an inflator pump, a sucking pump, a gas-pressure meter and a connecting rubber pipe. By adopting the flexible wall protecting device of the hydraulic support, the coal wall fluctuation state can be adapted, a supporting mechanism and a coal wall can be sufficiently attached to sufficiently and evenly apply supporting force to the coal wall, the coal wall is protected to the utmost extent, the stability of the coal wall is improved, and thus the wall caving probability of the coal wall is lowered; and the situations that a rigid wall protecting plate cannot make sufficient contact with the coal wall, consequently the wall protecting plate and the coal wall are in line contact and even point contact, the local supporting force of the coal wall is too large, then the coal wall is damaged, and wall caving is caused are avoided, and the problem that a hydraulic support wall protecting plate with a large-mining-height working face cannot effectively protect the coal wall, and consequently wall caving is caused is solved.