The utility model relates to a control pressure drilling apparatus based on double gradient, which is characterized in that: the utility model comprises a drilling apparatus consisting of a drill rod, a while-drilling injection joint, an underground safety valve and a drill bit, a slurry treating device, a central control system and a sea surface low-density fluid flow rate control device; the drill rod is a double-wall drill rod; corresponding to the drill rod, the while-drilling injection joint is a double-wall drill rod segment having an inner pipe and an outer pipe; a centering rib is connected between the inner pipe and the outer pipe; two ends of the inner pipe and the outer pipe are respectively connected with the double-layer wall surfaces of an upper drill rod and a lower drill rod into a whole through threads; the circumferential wall surface of the outer pipe is provided with three to four through filling orifices; the inside of the pipe wall above each filling orifice is provided with a pressure regulation control device; the bottom surfaces of the pressure regulation control devices are connected with a flashboard driving device; the tail end of the flashboard driving device is connected with an arc-shaped flashboard; the bottom of each filling orifice is provided with a pressure passing hole extending downward; the tail end of each pressure passing hole radially penetrates through the outer wall of the outer pipe. The utility model can be used for offshore drilling as well as onshore drilling.