Abstract: A new method for calculating the damage index was first proposed-point load strength method (PLSM), based on the scene point loading strength test results and the damage theory. In order to verify the reliability and accuracy of the method and demonstrate the relationship between the damage index and integrity index which has been computed using this method, a series of theoretical inferences, in-situ rock mass acoustic tests and the lab rock acoustic tests have been carried out. The results show that the damage index and rock mass integrity coefficient have good consistency. The damage index calculated by using this method is correspondent with the change trend of rock mass damage extent within the scope of the loose circle. The error value of measured and theoretical values is less than 7%. It shows that calculating the damage index through the method has high accuracy and reliability.