The invention discloses a PTC liquid heater and belongs to the technical field of liquid heating device design. The PTC liquid heater comprises a pipeline, PTC heating bodies and a runner cavity. The PTC heating bodies and the runner cavity are arranged in the pipeline. The runner cavity comprises a first runner cavity body and a second runner cavity body which are both longitudinal channels for circulation of liquid in the longitudinal direction of the pipeline. An upper locating groove and a lower locating groove are formed in the pipeline. Both the first runner cavity body and the second runner cavity body are arranged between the upper locating groove and the lower locating groove. The two PTC heating bodies are arranged in the upper locating groove and the lower locating groove respectively. The PTC liquid heater is reasonable and simple in structure, easy to produce and manufacture and convenient to use; an existing PTC liquid heater is improved, in the specific use process, the liquid heating acceleration effect is achieved, heating efficiency is improved, and the simultaneous heating water amount is guaranteed; and meanwhile, water is divided into two runners and heated respectively, the amount is guaranteed, the heating speed is increased, and heating efficiency is improved.