Abstract: The structural changes of silicon manganese containing master alloy and the distribution conditions of manganese and silicon components have been observed. The results shows that liquid phase sintering appears at a temperature over 1100℃ after the addition of silicon and manganese master alloy. However,only the pores left after the master alloy particles of small size have been dissolved approach to spherical shape,while ring shaped pores are left around the master alloy particles of lager sizes. The structure of original larger silicon manganese master alloy changes with temperature increasing. The diffusing process of manganese and silicon components to matrix will substantially speed up due to the presence of liquid phase.