The invention discloses a multi-channel hole sealing device, a hole sealing assembly and an automatic hole sealing method. The multi-channel hole sealing device includes a plurality of pipe bodies coaxially arranged in a sleeving mode, and the adjacent pipe bodies at least form setting grouting channels, gas-back grout channels and extraction channels; setting capsules are further coated outside the pipe bodies, and the setting capsules are further connected with axial compression self-locking pieces, and self-sealing fluids from the setting grouting channels provide power for the axial compression of the axial compression self-locking pieces. The multi-channel hole sealing device has a series of functions such as setting, grouting and gas back, and the integration degree, thereby greatlyreducing complexity of the construction procedure; with the help of loading and unloading drill pipe functions of a drilling robot, automatic entry of the hole sealing assembly is realized, and seriesof operation of automatic setting, grouting, pressure building and diffusion and the like are realized through a control system; and the number of workers on spot is reduced and the automation of borehole hole sealing operation in underground gas extraction in a coal mine is realized, and the multi-channel hole sealing device, the hole sealing assembly and the automatic hole sealing method are ofgreat significance for improving the level of mine safety production, reducing labor intensity and reducing safety risks.