In this paper, we present a systematic computational study based on the density function theory (DFT), Which aims to shed light on the potential effects of doped gold Au clusters with a platinum Pt atom,and finding the new structural and electronic properties that will be enjoyed by gold doped with platinum PtAun (n = 1-9) clusters, So that the most stable clusters are selected from the rest of the isomers for each cluster size. We doped Aun clusters with Pt atom, we obtained very interesting results, Stable and most stable structures reveal three-dimensional structures starting from (n=6), Also, the results of the fragmentation energy and the second difference in binding energy of these clusters in relation to their size have been studied in depth. The electronic properties, such as the Homo-Lumo gap energy, Vertical ionization potential (VIP) and adiabatic ionization potential (AIP) as a function of cluster size are also studied and discussed. All properties calculated by the generalized gradient approximation (GGA) were compared with the results of the local density approximation (LDA). Whereas, the results showed that the Aun clusters doped with Pt atom changed significantly.