Metal O-rings are widely used as static seals in industrial equipment in the petrochemical, aerospace, nuclear power, and other fields. In view of the problem of trace leakage of metal O-rings during the operation of the equipment, a leakage model of metal O-ring seals was obtained based on modified fractal theory and laminar flow theory. After establishing the leakage model by numerical simulation, the seal performance experiment of the metal O-ring seal was conducted, and the rationality of the leakage model was verified using the test data, and the influence of the fractal dimension of the seal face, the characteristic scale, and the pressure difference between two sides of the seal face on the leakage rate of the metal O-ring was analyzed. The results show that the leakage rate decreases with the increase of the fractal dimension when the seal face load and the characteristic scale are the same, and decreases with the decrease of the characteristic scale when the seal face load and the fractal dimension are the same. Realizing the accurate calculation of its seal leakage rate is of great significance in evaluating the safety and reliability of industrial equipment.