In metal matrix composite, the matrix and reinforced body is different in physical and chemical properties. The transition effect of reaction zone between the matrix and reinforced body is the hot point in research aboat metal matrix composite. The steel substrat casting tungsten carbide particle surface reinforced compostie is research object in this article. The interface reaction zone is measured by EDS line scaning. The problem is solved by statistic that interference between scaning neighbour points leads to the emergence of sawtooth wave, the processed curve is beneficial to observe. The effect and effect curve of W、Mo、Ni addion is received in the interface reaction zone.