Abstract: For deficiencies of its structure, the previous breather valve with fire protection is not suitable for installing on light oil storage tank at cold area. In the paper, it has been described that the new weatherproof breather valve replaces the old 68-1A breather valve with fire protection and that the improvement of structure and the adoption of new material make the surface contacting form of valve seat improving from its hard structure contact to its soft air seat contact, so that the purpose of frozen crack provention and close seal being achieved, the leakage of oil and gas being provented and the safety of operation being assured. The paper also introduces all data tests for the valve.