A low serum medium(LSM) suitable for the growth of a self-constructed hybridoma cell line, KA112, was established by selecting ingredients to replace serum. Insulin and sodium pyruvate was important for the growth of cell line KA112. Various basal media were tested and DMEM gave the most favorable result. Low serum medium (LSM) developed in this work showed cell line stability in the culture for more than 6 months and exhibited cell growth equivalent to that carried out in medium supplemented with 7% FBS. LSM was found to be applicable to the suspension culture of KA112. The reduction of serum level down to 1%(V/V) FBS in LSM resulted in a substantial saving in the cost of media preparation for large scale culture.