In view of the temperature distribution of the exhaust muffler shell of a certain type of dangerous goods transporter and whether the external excitation will cause the resonance of the muffler which may cause the cracking of the muffler or not, the FLUENT software is used to analyze the internal flow field and the temperature field of a muffler. The AR320 + noncontact infrared thermometer was used to measure the temperature of the muffler shell. Finally, based on ANSYS Workbench, the prestress which were numerical analysis results were used to conduct modal analysis for mufflers. The research shows that the error between the temperature simulation value and the test value of the muffler shell is within 5.92% and the accuracy of the numerical analysis is indirectly verified. When the velocity of exhaust gas is 6.24 m/s, there is a eddy in the muffler which will cause noise. And the frequency of road surface excitation 27.8 Hz and the frequency of engine excitation 10667 Hz are both lower than the first order natural frequency 111.01 Hz of the muffler, it will not cause resonance, but the deformation of the left side of the muffler cylinder is 18.06 mm which is the weak position of the muffler. The research results can provide solid reference for improving design of mufflers for special vehicles.