Abstract: To understand the heat transfer characteristic between mechanical seals and flushing fluid in super-speed condition and to obtain the intensity of the heat transfer, a fluid-solid model of the mechanical seals is built based on the numerical calculation method. Subsequently, the temperature field is calculated, the temperature distributions of some surfaces are achieved. Moreover, the convection heat transfer coefficient is calculated by the formula, which coincides with the analytic solution. It is concluded that the calculated convection heat transfer coefficient is accurate; the heat transfer capability of the flushing liquid in contact with moving loop is slightly higher than that in contact with static loop; the heat transfer on some walls can be significantly enhanced by increasing the flow rate of flushing liquid at inlet.