Abstract: In order to explore the decalcification technology of yellow croaker scales,the decalcification condition of the yellow croaker scale was optimized by using citric acid as decalcification agent under the ultrasound-assisted treatment. Three factors including solid-liquid ratio,citric acid concentration and ultrasonic time were selected to investigate the effects of decalcification on yellow croaker scales. The single factor experiment was carried out with the decalcification rate as the evaluation standard to determine the single factor optimal level. On this basis,the Box-Behnken design was adopted to optimize the decalcification of fish scales,and the optimal conditions for decalcification of the yellow croaker scales were obtained as follows,solid-liquid ratio 1:19 (g/mL),citric acid concentration 10.5%,ultrasonic time 65 min,with the demineralization ratio 99.18%. The results also showed that the loss rate of collagen was 4.08% under the optimal conditions,and the loss rate was relatively small. Therefore,the ultrasound-assisted citric acid treatment had a good effect on decalcification of yellow croaker scales,which would provide a basis for further research on extraction of collagen from yellow croaker scales.