Abstract: In this paper,normal pressure infiltration of pure magnesium into B₄C particle base plate with different compactibilities was studied,and the influence factors on the normal pressure infiltration are discussed.An infiltration model is suggested.It is shown that the magnesium can infiltrate into the gathering preform of B₄C particles in a range of temperature from 800 to 850℃ for 30min under the condition of Ar atmosphere.The depth and the width of infiltration increase as the temperature and time increase.B₄C_P/Mg composite obtained by the method of normal pressure infiltration has high hardness,and B₄C particles are dispersed homogeneously in the magnesium matrix.