According to the performance tests in BA- 103 cracking still, the effect of the transformed stove has been gained. The tests have shown that in the cracking still, the temperature distribution in the gas and the wall setting as well as the cracking tubes can meet the design requirements. The loss of heat dissipating is smaller, indicating the insulating layer design of the stove wall and the installation have been properly made; the thermal loss of the exhaust gas is more because the excess air coefficient is big and the gas temperature is higher. The thermal efficiency of this stove satisfies the design requirement, and the transformation of the cracking still has achieved the purpose in saving energy, reducing consumption and increasing the output.