In laser diode array (LDA) end-pumped large-aperture amplifiers, coupling system with high efficiency and uniform pump distribution is very important. To evaluate different coupling systems, a set of evaluating specifications is put forward, including depositing efficiency, mean pump intensity, modulation, fluctuation root-mean-square (RMS) and size of uniformly pumped region. In these specifications, depositing efficiency, mean pump intensity and fluctuation RMS are statistical variables, and modulation is extreme variable. Dimension index of uniformly pumped region under certain conditions is obtained based on the statistical variable fluctuation RMS. A new method of calculating these values is put forward. The variation curves of these indices are obtained through calculating the pumping area gradually. When the analyzed region is as large as the whole pumping region, varying trends of these specifications can be given out. Using these trends, different coupling methods can be compared. Calculating example of there different pumping fields shows that this set of specifications is comprehensive and is valuable to assess different coupling systems.