The invention provides a grain noise detection fixture, which comprises a base, and a clamping frame on one side of the base and integrally formed with the base. The clamping frame and the base are enclosed to form a cavity for accommodating a to-be-detected element. The clamping frame is provided with a fastener mounting hole in communication with the cavity. The invention also provides a grain noise detection device provided with the above grain noise detection fixture, and a grain noise detection method. The method comprises the steps of a1, removing surplus materials in a to-be-detected circuit; a2, covering a circuitron cap of the to-be-detected circuit onto a tube socket of the to-be-detected circuit without packaging the circuit; a3, fastening the to-be-detected circuit with the circuitron cap covered thereon into the fixture; a4, placing the fixture onto a grain noise tester for noise detection. By means of the grain noise detection fixture, the grain noise detection device and the grain noise detection method, the to-be-detected circuit can be pre-detected before being packaged.