Pressure-controlled drilling system

A pressure-controlled drilling system comprises a drilling pump, an automatic throttle manifold module, a circulation tank, a drilling tool, a main circulation module and a bypass shunting module. The well drilling tool comprises a rotary control head, a well killing pipeline and a throttling pipeline, wherein the well killing pipeline and the throttling pipeline are used for forming a wellbore annulus. The main circulation module comprises a main circulation pipeline and a main circulation valve group arranged on the main circulation pipeline; the bypass circulation module comprises a bypass circulation pipeline and a bypass circulation valve group arranged on the bypass circulation pipeline; the automatic throttle manifold module comprises a throttle pipeline and a throttle valve group arranged on the throttle pipeline; according to the pressure control well drilling system, through the arrangement of the bypass shunting module, the use of a back-pressure pump system is avoided, in the well drilling process