The invention relates to a well drilling gas injection joint applied to the technical filed of petroleum drilling. The upper end of a main body is drilled with a longitudinal hole communicated with a horizontal hole; the inner end of the horizontal hole is a round hole and a valve core is arranged in the horizontal hole; one end of the valve core matches with the round hole at the inner end of the horizontal hole, which plays a sealing role, the other end of the valve core is fixed with a positioning disk and a spring is positioned between the positioning disk and a plug; high pressure air istransmitted to the horizontal hole through the longitudinal hole, the positioning disk is provided with a through hole, the spring is an helical extension spring and the thread of the longitudinal hole is fixed with a pipeline joint. The application process comprises the following steps of: A. putting down a bushing: the well drilling gas injection joint is connected on the pipe column of the bushing; B. well cementation; C. connection with a ground gas injection system; D. drilling construction; E. the injection of high pressure gas into the bushing; and F. stopping gas injection. The well drilling gas injection joint can effectively reduce annular hohlraum inner fluid column pressure and fulfill the purpose of safety, quick and high efficient drilling.