The present invention provides a chromium-free coating composition having high blackening resistance and corrosion resistance, the composition comprising: 20 to 70 wt % of waterborne silane modified polyurethane; 0.5 to 5 wt % of a hardener; 0.5 to 5 wt % of a blackening inhibitor; 0.5 to 5 wt % of a corrosion inhibitor; and 0.5 to 5 wt % of a lubricant, with the balance being a solvent. The chromium-free coating composition has the effect of improving blackening resistance, corrosion resistance, alkali resistance, solvent resistance and fingerprint resistance of a steel sheet on which a coating layer comprising the composition is formed.