The invention discloses a small quick heater which comprises a shell, insulating layers, insulating studs, a heating net, electrodes and asbestos gaskets, wherein the heating net is fixed on the insulating studs on the two sides of a channel of the shell in a tensioned mode to enable a multi-layer grid structure to be formed in the channel, the electrodes are arranged at the two ends of the shell respectively to fasten the heating net, the power supply ends of the electrodes and flanges are fastened to the shell through insulating screws, the insulating layers are arranged between the electrodes and the shell, the asbestos gaskets are arranged between the electrodes and the flanges, and the heating net is electrified and heated through the electrodes to achieve reliable power supply. According to the small quick heater, multi-layer folding wire mesh is adopted to serve as a heating element, the wire mesh is arranged perpendicular to the liquid flowing direction in a single-layer or multi-layer mode, and by means of the characteristics that the contact area between liquid and the heating element is large and heat exchange is strong, the efficiency of heat exchange between the liquid and the heating element is high. The heater is used for quick heating of liquid working media in a channel under the condition that non-conducting liquid is still or moves, and especially suitable for quick heating of liquid with small flow.