Abstract: The traces of ordinary flat glass under thermal stress and mechanical stress are simulated. The macroscopic characteristics of the traces are analyzed. The influence of the intensity of fire source on the traces of thermal damage and the correlation between the crack characteristics of glass fragments and the direction of force are studied. The experimental results show that a main crack and several split cracks propagating in different directions are formed at the center edge of the glass when the glass is hot-exploded. The greater the intensity of the fire source，the more split cracks are produced at the main root of the dendritic crack，and the more they aggregate towards the main crack. The characteristics of the arch and the location of the fragmentary cracks is closely related to the direction of force，and it is inaccurate to only base on the location of broken teeth and the characteristics of arch lines in field investigation.

Key words: thermal cracking of glass, mechanical damage, glass fragments, arch pattern characteristics, broken tooth marks, force direction, fire investigation.