Abstract: A torque-adaptive impact tool suitable for a PDC (Polycrystalline Diamond Compact) bit is provided, which includes a PDC bit, a rotary-driving power device, and a torque-adaptive impact tool above the PDC bit. The torque-adaptive impact tool is located between the PDC bit and the rotary-driving power device, includes an outer housing, an upper end cover, a main shaft, an elastic element, an upper impact body, and a lower impact body. In a case of a normal operation of the bit, the tool does not impact the bit, but rotates along with the rotary-driving power device for drilling. In a case that a rock-breaking torque required by the bit exceeds a driving torque, the tool impact the bit.