Abstract: Resonance Rayleigh scattering method with trypan blue was applied to the determination of calcium in apples. In Tris-hydrochloric acid buffer solution of pH 6.50, trypan blue reacts with calcium(Ⅱ) and cationic surfactant hexadecyl trimethyl ammonium bromide (CTMAB) to form a ternary ion association complex, which led to a distinctly enhanced resonance Rayleigh scattering (RRS) signal of the system. The maximum resonance Rayleigh scattering peak was located at 348 nm. The optimized conditions found were as follows:① amount of Tris-hydrochloric acid buffer solution of pH 6.50 was 2.00 mL; ② amount of 1.0×10^-4mol·L^-1 trypan blue solution was 2.50 mL; ③ amount of 4.00×10²mg·L^-1 CTMAB solution was 0.40 mL; ④ time of reaction was 25 min. Linear relationship between values of enhanced RRS intensity (ΔI_RRS) and mass concentration of calcium was obtained in the range of 0.007 0-0.080 0 mg·L^-1, with detection limit (3s/k) of 0.001 3 mg·L^-1. The proposed method was applied to the analysis of apple samples, giving values of recovery and RSDs (n=6) in the ranges of 98.3%-102% and 1.8%-2.3% respectively.