On the basis of analyzing the method for classifying the unloading zones of Emeishan basalts in the project site of a hydroelectric power station in southwestern China, the authors adopt three indexes, that is, opening joint quantity, joint opening degree and wave velocity that have been exercised by many projects as quantitative indexes for classifying the unloading zones. And, they divide the unloading zones of the Baihetan hydroelectric power station using the above three indexes for proving the feasibility of taking the three quantitative indexes as unitive classification standard. Farther, the authors discuss the unitive standard and bring forward the proposition of classifying the unloading zones of Emeishan basalts.