Abstract: The principle of the cable-in-rod through pump heating technique is:refit the conventional well pump into hollow annular flow one, let hollow rod directly pass through the pump to get to a certain depth underneath it, and then place a cable in the hollow rod, thus, by means of skin effect, the crude oil above, below and in the pump is heated, the crude oil viscosity and the resistance of it into the pump are reduced, the oil output of the well is enhanced. This technique is successful in filed test, and has become the necessary oil producing technology in development of the field with extra viscous crude oil.