An outer rotor type electronic pump , comprising a first housing , a second housing , a rotor assembly , a stator assembly , a shaft and a printed circuit board , a pump chamber comprises a space between the first housing and the second housing , a partition which is integrally injection-molded with the second housing separates the pump chamber into a wet chamber and a dry chamber , the rotor assembly is arranged in the wet chamber , and the stator assembly and the printed circuit board are arranged in the dry chamber , wherein the rotor assembly comprises an impeller , a rotor , a metal ring , and a metal sleeve , the impeller and the rotor are separately formed, the material of the impeller comprises no magnetic material, and the material of the rotor comprises a magnetic material, and the impeller and the rotor are fixed with respect to each other by the metal ring and the metal sleeve , the impeller comprises blades , a first connecting portion and a second connecting portion , wherein the blades , the first connecting portion and the second connecting portion are integrated, the second connecting portion is an incomplete cylinder, the second connecting portion comprises a fixed portion and a free end, the fixed portion of the second connecting portion is fixed to the first connection portion , and the free end of the second connecting portion comprises a first fitting portion , the first fitting portion comprises a first protrusion and a first sunken portion which are alternately arranged, and the first connecting portion comprises an upper surface and a lower surface, the blades are integrally connected to the upper surface of the first connecting portion and extends therefrom, and the second connecting portion is integrally connected to the lower surface of the first connecting portion and extends therefrom, the extending directions of the blades and the second connecting portion are opposite to each other, the rotor comprises an end and a rotor side wall , the end is arranged at an end of the rotor side wall , the end of the rotor comprises a second fitting portion , the impeller and the rotor are fitted by the first fitting portion and the second fitting portion , the second fitting portion comprises a second protrusion and a second sunken portion , the first sunken portion and the second protrusion are engaged with each other, and the first protrusion and the second sunken portion are engaged with each other, wherein at least part of the metal ring and metal sleeve is arranged at the cooperation between the impeller and the rotor , wherein the cooperation is formed by the first fitting portion and the second fitting portion , wherein the metal sleeve has an L-shaped cross section and comprises a cylindrical portion and an annular bottom , the cylindrical portion at least covers the cooperation between the impeller and the rotor , and the annular bottom covers at least part of the first connecting portion of the impeller , thereby the metal sleeve will not fall off in a direction of the rotor , an annular groove portion is formed on the rotor at the joint between the second protrusion and the rotor side wall , the metal ring is sleeved in the annular groove portion , and is partly arranged into the annular groove portion , the metal sleeve and the metal ring are fixed by welding, which further allows the impeller and the rotor to be fixed. <EOS>