By investigating the time integrated spectra, the kinetics of Kr2F* in fast discharge excited He/Ar/Kr/F2 mixtures have been studied, the paths feature of the formation of Kr2F* have been probed. According to the theoretical analysis and the experimental results, it was shown that under the fast discharge excitation, the three-body collision reactions KrF* + Kr + M→Kr2F* + M are the main paths to the formation of Kr2F* and KrF* can be formed efficiently via displacement reaction ArF* + Kr→KrF* + Ar. The corresponding formation rate constants of Kr2F* have been measured by the experiments.