Abstract: Grapefruit peel was processed with ultrasonic, and then adding complex pectinesterase to extract pectin, which could reduce the pollution of inorganic acid.The infrared spectrum showed that grapefruit pectin contained a relatively huge amount of carbohydrates, but no protein.Basic on the single factor experiment, the extract technology was optimized by orthogonal experiments at 240W ultrasonic power, 24kHz requency, 20min ultrasonic processing time, 50min single extraction time, buffer pH 5.5, 55℃ pectinesterase extraction temperature, 0.9% enzymatic dosage.The average quantity in grapefruit peel pectin was 236.2mg/g, which was much higher than the pectin extraction quantity using conventional water bath method under the same conditions.