Six Al0.3CoCrFeNiCx (x = 0, 0.02, 0.04, 0.06, 0.08 and 0.1 in molar ratio) high entropy alloys were synthesized by induction melting in air. The characteristics of microstructure and tensile properties of the as-cast alloys were investigated. All alloys exhibit a FCC solid solution matrix, and the eutectic carbides are observed in alloys when x ≧ 0.04. With lower Cr/C ratios, the (Cr,Fe)23C6 k2 carbide transforms into (Cr,Fe)7C3 k1 carbide. Tensile tests show that the strength increases and elongation decreases as carbon content increase. While x ≧ 0.06, the formation of a net-like k1 carbide results in the drop-off on elongation, and the fracture surfaces change from dimple-like fracture into cleavage fracture.