The invention discloses a power matching method based on torque and rotation speed compound control for a rotary drilling rig. The power matching method comprises the following steps: calculating target current according to pressure of a primary pump and a secondary pump and set target torque percentage; setting a speed drop value during interconversion of a rotation speed regulating module and a torque regulating module; when a real-time speed drop value of an engine is smaller than a set value, adopting the torque regulating module to carry out compensation regulation on target current; when the real-time speed drop value of the engine is greater than the set value, adopting the rotation speed regulating module to carry out compensation regulation on the target current; and outputting a final current value to an inverse proportion pressure-reducing valve to control a displacement regulator to change displacement of the primary pump, thereby controlling input power of the primary pump in real time. The power matching method is simple, reliable and high in practicability, has the characteristics of rotation speed control rapidity and torque control predictability, can effectively avoid severe speed drop of the engine, avoids a shut-down phenomenon, improves operation efficiency of the rotary drilling rig and guarantees operation stability of a control system.