According to the theory that the independence is equivalent to the uncorrelation, a description of joint probability distribution of finite discrete random variable is found. Through extending the values of two-state to that of multi-state, when two random variables' marginal distributions and right high steps correlative coefficients are given, two dimensional joint probability row can be got to make independence and uncorrelation have an integrated description and expressive form.. This method is verified through simulations. By the way, the expression obtained is applied to the analysis of data channel communications. The in-out information coupling is described by channel's port correlative coefficients, which is a fine supplement to the information theory. This method is corresponding with information theory's average mutual information and data processing theorem, and a perfect formula and ideal characteristics are obtained.