In this thesis, we have two parts to present. In the first one, we investigated luminescence mechanism of Bovine Serum Albumin-coated gold nanoclusters by photoluminescence (PL), and time-resolved photoluminescence (TRPL) experiments at different temperatures. In the carrier recombination process, we observed the confinement effect in our sample. By measuring the TRPL at low temperatures, the activation energy at different temperatures can be fitted. We also obtain localized depth of carriers in our sample, suggesting the luminescence mechanism of AuNCs@BSA. In the second part, we explore the effect of rapid thermal annealing (RTA) on the PL of gold nanoclusters. We obtained the carrier recombination time by the TRPL experiments. PL intensity is enhanced by 1.2 time after rapid thermal annealing.