An electric heater capable of heating continuously comprises a supporting frame, a machine body and electric heating pipes. The machine body is fixedly assembled on the supporting frame and internally and detachably provided with an electric heating pipe alternating device. A hand lifting ring is arranged on the supporting frame. The electric heating pipe alternating device comprises an assembling body. The assembling body is internally provided with a left sliding groove, a right sliding groove and a through cavity, wherein the left sliding groove and the right sliding groove extend front and back and are opposite to each other, and the through cavity penetrates the left sliding groove and the right sliding groove and are connected with the left sliding groove and the right sliding groove. The left sliding groove and the right sliding groove are movably provided with a left sliding block and a right sliding block correspondingly, and a first electric terminal and a second electric terminal are fixedly arranged at the upper end of the left sliding block and the upper end of the right sliding block correspondingly. The electric heater is simple in structure, sable in operation, small in electricity consumption and capable of achieving continuous heating.