Microstructures, phase stability and properties of the as-solidified CoCrCu0.5FeNi(Si/B)x alloys were studied in this work. Intermetallic compounds are found when Si or B was added in a FCC structural CoCrCu0.5FeNi high-entropy alloy, and B possess a better intermetallic formation ability than Si. On the other, solute ability of Si is better than that of B in CoCrCu0.5FeNi alloy. The strength of CoCrCu0.5FeNi high-entropy alloy was improved after the addition of Si and B, and the strengthen mechanism was discussed. Moreover, parameter g can provide a reference to predict the ability of forming intermetallic compounds in CoCrCu0.5FeNi(Si/B)x alloys. The increase of δ is prone to the forming of intermetallic compounds. But the volume fraction of intermetallic compounds increase with the decrease of Ω in the same alloy system.