PURPOSE: To obtain ferrosilicon in a high Si yield and a low coke ratio, in a method for preparing the same by blowing an O2- containing gas into a furnace into which a silicic acid-containing raw material, coke and an iron raw material are charged, by specifying the O2 content in the blowing gas and the feeding amount thereof and the particle size of coke.

CONSTITUTION: A silicic acid stock material such as silica rock, coarse coke with a particle size of 30mm or more and iron scrap or iron ore are charged into a furnace 2 from the top thereof and a gas containing 70% or more oxygen is introduced into the floor part of the furnace in an amount of 0.20W1.4Nm3/m2s per the furnace cross area of a gas introducing tuyere part. In this case, when the O2 concn. in the gas is below 70%, the gas temp. of the furnace top is raised to a high temp. not endured by a usual steel plate and a coke ratio is abruptly increased and an Si yield is rapidly lowered. When the particle size of coke is equal to or lower than 30mm, the coke ratio is extremely increased. Whatever the supply ratio of O2 may be too high or too low, the coke ratio is increased and the Si yield is lowered. In addition, directly after the waste gas from the top of the furnace 2 is subjected to coarse dust collection according to necessity, the collected dust is burnt in a chamber 4 and the heat of the combustion gas is recovered in a boiler.