Nowadays, the artificial imitations of obsidian in jewelry markets are very similar to the natural obsidian in appearance, basic properties and substance composition. This may confuse the consumers and challenge the routine testing. Taking the natural and artificial obsidian as the objects of study, a method which combines the infrared reflectance spectroscopy with the transmission spectroscopy is used to analyze the difference between the natural obsidian and its artificial imitations. The results show that both of them are amorphous SiO2 substances, i.e. vitreous substances. Due to their different formation processes and medium environment, they have different degree of spectral division in the infrared spectral fingerprint region from 600 cm-1 to 1400 cm-1. In the characteristic frequency region from 2600 cm-1 to 3700 cm-1, the position and strength of their H2O and O-H vibration absorption bands are also different. The results provide a new technical idea for the rapid, accurate and nondestructive identification of obsidian.