A PTC (Positive Temperature Coefficient) liquid heater, comprising: a heating assembly, comprising: a heat conductor having at least one accommodating cavity, a PTC heat generation assembly disposed in the at least one accommodating cavity, a sheath having a cavity for accommodating the heat conductor and the PTC heat generation assembly, anda housing having a water inlet and a water outlet, wherein the heating assembly at least partially passes through the housing. The PTC liquid heater of the present invention has a better corrosion resistance, and can greatly extend the service life of the liquid PTC heater and prevent electric leakage accidents. The PTC liquid heater has a simple structure and low costs, and is convenient to assemble, especially in that the water pipes can be replaced, facilitating future maintenance.