A new method for evaluating petroleum reserve—transformation of empirical distribution(TED)—is studied in this paper.The TED method can be applied to obtain the probability distribution of petroleum reserve based on the equation Z=R.X.Y.Here X and Y are random varibles representing certain geological or reservoir parameters

R is a constant coefficent and Z

the amount of petroleum reserve.The main points of the TED method are as follows:(1)the"density matrix of joint distribution"is used to be the approximation of the population distribution density func-tion of X and Y;(2)a group of numerical computation formulae for trans-formation of random vector is then derived to produce the curve of probability distribution of petroleum reserve Z.Correct interpretation of reserve probability distribution is an important problem of quantitative appraisal of petroleum resources.This paper has also proposed a set of suggestive interpretation methods.