To compare the luminescence effect of different blue light pyrotechnic compositions and explore the new method of optimal design of formulations, the thermodynamic study on six kinds of blue light pyrotechnic compositions was carried out by REAL thermodynamic program. The relationship among the enthalpy of combustion reaction, flame temperature and emitted photon numbers of blue light pyrotechnic compositions was established. The formulation and proportion of blue light pyrotechnic compositions was optimized and selected based on the combustion flame temperature and photon numbers of emitted blue light obtained by calculation. Results show that the combustion temperatures of six kinds of blue light pyrotechnic compositions are 1651-2880 K, which is in accordance with the results calculated by NASA-CEA program. The photon numbers emitted at the maximum wavelenght are 0.02011-0.0435 mol·kg^-1 and the major emitter that produces blue flame is CuCl. With the help of the relationship among the enthalpy of combustion reaction, flame temperature and emitted photon numbers of blue light pyrotechnic compositions, the combustion temperature of the blue light pyrotechnic composites containing KClO₃, 2CuCO₃·Cu(OH)₂ and S is 1651 K. The emitted photon number is 0.0435 mol·kg^-1. The emitted effect of blue light is better in the six kinds of formulations. The optimal proportion of the formulation is KClO₃/2CuCO₃·Cu(OH)₂/S=63/19/18. It provides a new method for the design and optimization of the other light pyrotechnic compositions.