Laser-induced breakdown spectroscopy (LIBS) is employed to detect the elements released during tree burning. The elements in bark and tree interior were measured separately which shows that the bark absorbed heavy metal particles in the atmosphere due to barks exposure to the air. The fire would cause pollution and affect our environment by releasing some heavy metal elements (like Mn) when the bark is burning. Meanwhile, CN radicals produced by burning trees were obtained by LIBS. The temperature of CN can be calculated and fitted. It can be used as a means of intuitively reflecting fire temperature. Moreover, by calculating the plasma temperature of the element Ca under different laser energies, a linear relationship between the plasma temperature and the external excitation temperature is obtained. The change of Ca temperature is more closely related to the laser energy, and the Ca plasma temperature can truly reflect the laser-induced external excitation temperature. Comparing the Ca plasma temperature with the CN vibrational temperature, the temperature of Ca is generally higher than the temperature of CN, which is inferred to be accompanied by energy loss when C reacts in the air to form CN radicals.