The variety of fin structure induced by process variation can make the nano FinFET device present different electrical properties. This fact complicates their single event transient (SET) effects. Based on the calibrated standard SOI FinFET device at 14 nm technology node, five structures, including the types of bullet, triangle, stepped, semicircular and bottom elliptic, were built up in this paper. The correlation relationship between the characterization of SET and the parameters of the fin structure was analyzed. Their relevancies were obtained by the grey theory. The results show that the collection charge and deposited charge are significantly associated with the cross section area of fin. The peak value of SET current, peak value of electron-hole pairs generation rate and bipolar amplification coefficient, not only depend on the cross section area of fin, but also depend on the effective channel width. Their dependences on the effective channel width are more remarkable.