Abstract: In order to study the optimal extraction parameters of β-carotene in aril of Momordica cochinchinensis extracted by ultrasonic assisted with ethanol,the effects of ultrasonic power,ultrasonic time,ultrasonic temperature and solid to liquid ratio on the extraction content of β-carotene. Based on the single factor experiments,the L₉(3⁴)orthogonal designwas applied. Moreover,the effects of sunlight,temperature,pH and metal ions on stability of β-carotene were also studied. Results showed that the optimum extractive conditions were determined as follows:Ultrasonic power was 60 W,extraction time was 60 min,extraction temperature was 65℃,solid to liquid ratio was 1:20 g/mL. The content of β-carotene was 2.212 mg/g under this condition. The study on stability showed that sunlight and high temperature(100℃)were not benefit tothe storage of β-carotene,it was easy to decompose under this condition. Acidic condition had a hyperchromic effect,but alkaline and neutral condition had an opposite effect and lowered the retention rate. Na⁺,K⁺,Fe²⁺,Fe³⁺,Cu²⁺ and Zn²⁺ had different effects on β-carotene,Fe³⁺ had a strong hyperchromic effect on β-carotene while Fe²⁺,Cu²⁺ and Zn²⁺ had a hypochromic effect on it. The important significance was provided for efficient use of β-carotene in aril of Momordica cochinchinensis and the further processing of aril.