The acoustic velocity may reflect the overall physical property of a rock. Based on triaxiality acoustic velocity test of rocks

the relationship between surface acoustic velocity and acoustic velocity under different confining pressures

i.e. different buried depths

is researched. According to test data and the results of dual parameters’ regression analysis. the rocks’ acoustic properties increased with the confining pressure abiding by multinomial of math. The acoustic properties of different kinds of rocks have different rules with the change of confining pressure; thus

distinguishing lithology profile is one of the basic conditions to research and apply acoustic properties of rocks. Acoustic property of the same rock has larger discrepancies in different buried depths; so

the buried depth is an important factor to research acoustic properties of rocks

which can not be ignored.