An electric water pump apparatus may include a body having a stator chamber and a rotor chamber therein, a stator having a hollow cylindrical shape and being disposed in the stator chamber and generating a magnetic field, wherein the stator fluidly insulates the stator chamber and the rotor chamber, a rotor disposed in the rotor chamber and enclosed by the stator, wherein the rotor is rotated by the magnetic field, and a pump cover connected to the body and forming a volute chamber therein, wherein the volute chamber and the rotor chamber are fluidly-communicated through a connecting hole formed to the body and a coolant is supplied to the rotor chamber through the connection hole, wherein the stator includes a stator groove formed in an inner circumference therein and the stator groove is fluid-connected to the rotor chamber and the volute chamber through the connection hole.