According to the ignition characteristics and operating features of the semiconductor bridge (SCB) and the law of energy conservation, the approximate distribution of input energy of the SCB is analyzed, and the temperature-rising model of SCB is established before the melting point of bridge. By numerical calculation, the distribution curves of rising temperature are obtained with different input energy, dissipation coefficients and specific heat capacities, and the energy distribution curves with different input voltages are also obtained. The distribution rule of the curves show: when the capacitance value remains constant, the higher the input voltage is, the faster the temperature increases; the more the energy dissipates, the longer the melting point arrives; the greater the heat capacity becomes, the slower the temperature changes, and at the same time the longer the melting point arrives. Compared with the experimental result, the feasibility and the rationality of the model is validated.