The invention discloses a lost foam casting machining method of a vehicle front slave plate base and belongs to the field of pouring machining. The method includes the following steps that firstly, molten steel is smelted, wherein the molten steel is prepared from, by mass, 0.25-0.3% of C, 0.2-0.5% of Si, 0.5-0.9% of Mn, 0.4-0.5% of Ni and 0.3-0.4% of Cu; secondly, a foam mold model and a pouringsystem are manufactured, and the foam mold model is subjected to vibration ramming in a sand box; thirdly, the smelted molten steel is poured, so that the foam mold model in the sand box disappears, and a casting is formed; fourthly, after being cooled, the casting is taken out, and following cleaning is carried out. The defects that in the prior art, the machining labor intensity of the vehicle front slave plate base is high, and the machining efficiency of the vehicle front slave plate base is low are overcome, the machining labor intensity can be effectively reduced, the machining efficiency is improved, structural distortion of the front slave plate base can be avoided, the machining precision is guaranteed, and the machining percent of pass of products is effectively improved.