Polycarbosilane (PCS), an important precursor for manufacture of silicon carbide (SiC) ceramics, was prepared and analyzed to determine its chemical composition. The major elements of silicon (Si) and carbon (C) in Si-C backbones and side chains in PCS represent more than 80% with minor elements of oxygen and hydrogen being less than 20%. In this work, a conventional potassium silicofluoride volumetric method was explored and modified for establishing a standard routine procedure to evaluate Si content in PCS. The optimal conditions were investigated using an orthogonal designed four-factor-three-level normal experimental scheme. The suitable parameters and standard procedure to analyze Si in PCS were obtained.