Abstract: 【Objective】 In order to fully extract the calcium of fish bones and make high-value utilization of fish bone resources.【Method】 Bigeye tuna（Thunnus obesus） bones are used as raw materials to extract soluble calcium by hydrochloric acid. The calcium content in bigeye tuna bones is measured by high performance liquid chromatography-inductively coupled plasma mass spectrometry（HPLC-ICPMS）. Atomic absorption spectrometry was used to determine the calcium content in the extraction. Based on the optimization of hydrochloric acid concentration,liquid to material ratio,extraction temperature and extraction time in one-factor experiments,the three factors of hydrochloric acid concentration,liquid to material ratio and extraction time were further optimized by Box-Behnken design. The model feasibility analysis was carried out,and the actual value of calcium extraction rate was compared with the predicted value obtained by multiple regression fitting.【Result】 The equations fitted by Box-Behnken could be used to simulate actual conditions,and the modified process parameters were hydrochloric acid concentration 1. 00 mol/L,liquid to material ratio 14∶1,extraction temperature 80 ° C and extraction time 80 min,calcium extraction rate was 84. 21%.【Conclusion】 This study provided a theoretical basis for the calcium preparation from bones of bigeye tuna.