Only a few researchers mentioned the accuracy (error) of SrNd isotopic parameters although these parameters have been widely used both in the study of petrogenesis and rockforming material source. Obviously it's not scientific to use these parameters without mentioning accuracy explanation. Authors firstly derived the related calculation formulas of parameters' errors using the propagation law of errors. These parameters include initial ratios of Sr isotopes (87Sr/86Sr)t and Nd isotopes (143Nd/144Nd)t, εSr(t)、εNd(t)、and Nd isotopic model ages. The error of (87Rb/86Sr)s deponds on the contents of Rb, Sr and their measurement deviations; the error of (147Sm/144Nd)s determined by the contents of Sm, Nd and their measurement deviations. The influencing factors of (87Sr/86Sr)t are the values of (87Rb/86Sr)s and gological age, the determinate deviations of (87Rb/86Sr)s 、(87Sr/86Sr)s and geological age; the parameter (143Nd/144Nd)t have similar influencing factors. The errors of TCHUR and TDM deponde on the values of (147Sm/144Nd)s, (143Nd/144Nd)s and their errors. Besides the values of (147Sm/144Nd)s, (143Nd/144Nd)s and their errors, the value of geological age and its error also influences factors of TDM2. This study conducted SrNd isotopic parameters and error calculation for four granite samples from Guposhan pluton in Guangxi Provicen. Influence factors are analyzed in detail using isotope dilution mass spectrometry (IDMS) and high accuracy isotopic age in order to ensure the accuracy of these parameters. It is not advisable to use the test results of trace element because of unreliable results, especially for those samples with high concentration of Rb. The author suggests that researchers can provide corresponding accuracy explanation when they use SrNd isotopic parameters.