The present invention discloses a method using a bismuth based alloy as power-off element, comprising: a bismuth based alloy is used as the power-off element and a melting point of the bismuth based alloy is between 100° C. to 380° C.; when the power-off element is in an environment below the melting point, two conductive elements are mutually contacted and capable of conducting currents, whereas the power-off element is only receptive of the currents but does not serve as a medium for conducting the currents; when a working temperature of a switch or the socket is close to or exceeds the melting point, the power-off element loses rigidity and enables the two conductive elements to be separated from each other, thereby forming an electrically disconnected state.