Objective: This study aimed to improve the preparation efficiency seaweed iodine and reduce the cost. Methods: The ultrasonic assisted technology was applied in kelp extraction section. The ultrasonic-assisted extraction technology of seaweed iodine was optimized by single factor and response surface test design. The amino acid composition in the final product was analyzed by high performance liquid chromatography (HPLC). Results: The optimal extraction conditions were as follows: ultrasonic power 125 W, ultrasonic time 130 min and ultrasonic temperature 57 ℃. Under the control of these conditions, the extraction yield was 39.85%, which was 1.6 times higher than that without ultrasonic-assisted extraction. The seaweed iodine products contained 11 kinds of amino acids, including 2 kinds of essential amino acids and 2 kinds of umami amino acids, and diiodotyrosine was also detected. Conclusion: Ultrasonic-assisted preparation can improve the production efficiency of iodine in seaweed.