This paper, based on magnetic fluid dynamics, combined with the air leakage of sintering machine, proposes a new type of magnetic fluid sealing device in sintering machine. According to the sealing mechanism of MHD as well as Bernoulli equation, the sealing theory--pressure difference equation in static sealing by magnetic fluid is deduced for the actual model of sintering machine. By using ansys finite element simulation software, the two-dimensional numerical simulation of thermal magnetic- coupling inside of sealing device is set up, the effects of different temperature on the magnetic properties are analyzed and the best sealing performance is found, that is when the edge temperature of the sealing device is controlled from 30°C to 80°C.