Deformation modulus of rock mass is an important parameter applying to the design of rock engineering; although it can be obtained from various in-situ tests

it is expensive and time-consuming so that many middle-small scale projects and preliminary design phase of large scale projects can’t get this parameter through this method. For this case

many researchers have developed a lot of dependency relations between deformation modulus of rock mass and physico-mechanical parameters or rock mass classification such as RQD

RMR

Q system and longitudinal wave velocity of rock mass

etc. This paper firstly summarizes the existed methods of pre-estimating the deformation modulus and discusses its working conditions and estimated value. Paying attention to the method using longitudinal wave velocity to estimate deformation modulus and taking Maerdang dam project for example

the paper develops a prediction formula. By comparing to the estimated values by various methods

it is shown that the formula developed has a good concordance with Barton’s equation and can be used to pre-estimate deformation modulus of rock mass