The invention discloses a self-lubricating water and gas injection method of rotary excavation equipment. The method comprises the steps that central water and gas through holes are formed inside a rotating spindle and a drill rod and a drill bit connected with the rotating spindle, a rotating sealing sleeve is installed at a water/gas injection hole in the rotating spindle, a cavity is reserved between the rotating spindle and the rotating sealing sleeve, the rotating sealing sleeve is externally connected with a water/gas source, when the rotating spindle rotates, the rotating sealing sleeve and the external water/gas source are relatively fixed, and the rotating sealing sleeve and the rotating spindle rotate relatively; the cavity is filled with high-pressure water/gas through the rotating sealing sleeve, then, the high-pressure water/gas enters the central water/gas through holes inside the spindle, the drill rod and the drill bit and finally flows out from the bottom of the drill bit, and the self-lubricating effect on rock drilling of the drill bit is achieved. In the high-speed rotation process of the rotary excavation equipment, high-pressure water/gas is injected in the interior, water/gas flow successfully reaches the bottom of the drill bit and is sprayed out from the bottom of the drill bit, the drill bit in working can be effectively cooled and lubricated in time, rotary excavation can be promoted, and the construction progress can be improved.