There are many factors influencing gold content determination in jewelry by fire assay.According to the national standard GB/T 9288-2006 Gold Alloy Jewelry,Gold Content Determination,Cupellation(Fire Assay),the paper investigated the key technical parameters that influence the gold content determination results of pure gold sample,calculated the uncertainty degree of the method,and analyzed the cause for the uncertainty.The test determined the optimal conditions:silver and gold mass ratio is 2.1,cupellation temperature is 950 ℃,gold splitting twice and each time for 30 min;expanded uncertainty is 0.42 ‰,and the final determination result is (996.94±0.42)‰（k=2）;weighting in one-millionth scale can effectively reduce the result uncertainty.