Aim: To provide theoretical support for the utilization of betacyanins derived from red pitaya fruit in food processing. Methods: Firstly， investigation of the impact of extraction solution， solid-liquid ratio， pH of extraction solution， temperature and time on the yield of betacyanins extracted from the red pitaya peel， to optimize the extraction conditions. Secondly， the betacyanins extraction were subjected to UPLC-MS analysis for the determination of their content and structural characteristics. Finally， the impact of metal ions， including Cu2+ and Fe2+， on its stability was evaluated. Results: An optimal extraction condition of betacyanins from red pitaya peel involves using distilled water as the extractant， maintaining a solid-liquid ratio of 1∶5， adjusting pH to 5， and conducting at 30 ℃ for 60 min. The extract contained 6 monomers of betacyanins， with a concentration of 95.2 mg/g. The main monomers were phyllocactin and betanin， accounting for 46.5% and 34.4%， respectively. The addition of CuSO4 and FeCl2 has disturbed the stability of betacyanins， with CuSO4 having a greater impact than FeCl2. Specifically， CuSO4 caused a reduction in absorbance values and color changes even at concentration as low as 0.05 mg/mL， while FeCl2 accelerated the trend towards color change when added at concentration exceeding 0.10 mg/mL. Conclusions: The red pitaya peel waste presents a promising source of betacyanins， with a simple and feasible extraction process. However， the presence of metal ions such as Cu2+ and Fe2+ can negatively affect their stability， thus avoiding contact with copper and iron utensils during processing and storage is recommended.