Coal seam drilling pressure-maintaining sampling device

The invention discloses a pressure-maintaining sampling device for coal seam drilling. The pressure-maintaining sampling device comprises an outer cylinder assembly, an inner cylinder assembly, a drill bit assembly and a control execution assembly, the inner cylinder assembly comprises a sample storage assembly with an inner cylinder body and a ball valve switch assembly which is arranged at the front end of the inner cylinder body and is used for opening or closing the inner cylinder body in the front-back moving process; the drill bit assembly is located at the front end of the ball valve switch assembly, and the control execution assembly is located at the rear end of the sample storage assembly to push the sample storage assembly to move forwards or reset so that the ball valve switch assembly can be opened in the forward moving process or closed in the reset process. The drill bit assembly at least comprises a sampling drill bit capable of being opened or closed, and the sampling drill bit comprises a ho