A reflowable thermal fuse comprises a base, a housing, an elastic conductive element, a sensor and a restraining element. The base comprises first and second bonding pads and combines with the housing to form an internal accommodating space in which the elastic conductive element has first and second ends connecting to the first and second bonding pads, respectively. The elastic conductive element is operable to exert a resilient force which is able to sever the connection between the second end and the second bonding pad. The sensor connects to the second end and the second bonding pad to form electrical connection. The restraining element comprises a pressing member going through an opening of the housing and pressing the second end to resist the resilient force during reflow. After reflow, the restraining element is removed and thereby the reflowable thermal fuse is in an activation condition.