We compared two different ways of adding spikes in the chemical procedure of Re-Os age determination. One is that fusing The sample with NigH and N4O2 in the black lead crucible and the spikes of 185Re and 1900s were fused simultaneously with the sample. the oTher is that the sample was fused in the oxide of alumina crucible,eluted with hot water and Then The spikes were added to the solution directly raTher than being fused. The results from both procedures are the same but the cost of the latter is lower.