A controllable circuit protector for power supplies with different voltages includes a first fuse and a second fuse connected in series to each other, a first heating unit, and at least one second heating unit in parallel to the first heating unit. A connected end of the first heating unit is electrically connected to a series-connected node between the first fuse and the second fuse, and a free end thereof forms a control terminal. When a load is irregular, the control terminal is connected to a ground terminal through a switch. For power supplies with different voltages, the effective resistance of the first heating unit and a part of the at least one second heating unit not melting is altered without causing drastic change arising from voltage variation to the total heating power, and the first fuse or the second fuse can duly melt down to protect the load.