A testing socket includes a metal block, an assembly block, an analog ground probe pin and a digital ground probe pin. The metal block is formed with a concave portion and used to connect to an independent main ground. The assembly block is electrically isolated from the metal block, and detachably embedded in the recess, so that the metal block and the assembly block are assembled together to be a probe holder. The digital grounding probe is inserted in the metal block, electrically connected to the independent main ground through the metal block. The digital ground probe pin can be electrically connected to a device to be tested (DUT) and the independent main ground. The analog ground probe pin is inserted in the assembly block, and electrically connected to the DUT and another independent main ground.