The present invention relates to an [Alpha] particle blocking low-energy electron detection device. The device comprises a housing with an opening at one end of the housing, a vacuum seal window, an [Alpha] particle blocking layer and an electron detection device. The vacuum seal window is located at the opening end of the housing, and the vacuum seal window and the housing form a vacuum cavity; the [Alpha] particle blocking layer clings to the vacuum seal window, is located at the internal portion of the housing, is insulated from the housing and is configured to block the [Alpha] particles to pass through; the electron detection device comprises an electron detector, a high-voltage module and a signal collection module; the electron detector is located at the external portion of the housing, the anode of the electron detector is connected with the high-voltage module, and a signal output end of the electron detector is connected with the signal collection module; and the [Alpha] particles pass through the vacuum seal window to enter and remain in the micropores of the [Alpha] particle blocking layer. The defect is solved that low-energy electrons emitted by tritium cannot be directly detected in a high radon environment in the prior art.