The invention relates to an inside-laser coaxial powder feeding laser impacting and forging composite machining forming device and method. The device comprises a master controller, a pulse laser device, a continuous laser device, a temperature inductor, a coaxial powder feeding device, a visual tracking system, a workbench, a mechanical arm, a metal powder container and a gas container. The pulse laser device, the continuous laser device, the temperature inductor and the visual tracking system are all arranged above the workbench. The mechanical arm tightly clamps the coaxial powder feeding device, so that the coaxial powder feeding device is located between the continuous laser device and the workbench, and is coaxial with the continuous laser device. The coaxial powder feeding device communicates with the metal powder container and the gas container. The pulse laser device, the continuous laser device, the temperature inductor, the visual tracking system, the mechanical arm, the metal powder container and the gas container are all connected with the master controller. The inside-laser coaxial powder feeding laser impacting and forging composite machining forming device and method can solve the problems of insufficient fusion and incomplete fusion of the Gaussian light spot edges, inner defects of gas holes, incomplete fusion, cracks and shrinkage are effectively eliminated, and the inner stress state of a formed part is greatly improved.