Abstract: Objetive: studying the effect of additive concentration on electrical conductivity of No.45 transformer oil and hydraulic fluid of general equipment. Method: by means of YX1154 electrical conductivity tester of oil,and then discussing the correlation of electrical conductivity and traditional testing index. Results: it is seen that the electrical conductivity of the both oil was linear accretion along with additives concentration increasing and accorded with the results of antirust ability.So the proposed method not only can be employed to quality evaluation and quality monitoring in factory and dead storage but also in battlefield.