Two different analysis methods were applied and compared for determining high-resolution Sr/Ca ratio profiles of one modern (live-caught) and four fossil (dead-collected) Tridacna spp. samples from South China Sea. The Sr/Ca profile of Tridacna gigas in the South China Sea determined by Inductively coupled plasma optical emission spectrometry (ICP-OES) had well defined annual cycles and was significantly, negatively correlated with sea surface temperature, implying that they can be used as good proxies of historical Sea Surface Temperature (SST). ICP-OES is an commonly used method for measuring Sr/Ca ratios in Tridacna spp. shells, but it needs ex-situ, time-consuming chemical pretreatments using variable acids and considerable amounts of sample. While the synchrotron radiation X-ray fluorescence (SR-XRF) technique does not have these shortcomings, it requires little sample preparation and allows rapid in situ analysis of solid-state samples at high spatial resolution (submicron scales), and it is characterized by non-destructive, high sensitivity, and multi-elemental distribution. In this study, we tested the feasibility of determining chemical elements in shell samples of Tridacna spp. by using SR-XRF. To the best of our knowledge, no similar studies have been reported in the literature.Our study showed that the data of SR-XRF can reflect the elements contents and their ratios change. SR-XRF derived Sr/Ca ratio profiles are significantly correlated with those from ICP-OES (P-values for five Tridacna spp. samples are all <005); therefore, SR-XRF can be a promising alternative to ICP-OES. And it has a broad application potential in palaeoclimate reconstructions by using Tridacna spp.