Ultrasonography was performed to determinate the sex and maturity of sturgeons.Sex differences were shown by the echogenicity and the morphology of ovaries and testes.Ultrasonic images of Acipenser baer at different developmental stages were also collected.A total of 20 553 sturgeon individuals which were 2 or 3 years old were examined using ultrasound scanning from February,2006 to March,2008.Results of ultrasonography were further confirmed by necropsy with random sampling.Ultrasonographic method was proved to have 92.00%-100.00% accuracy rate in sex determination of 2 or 3 years old A.baeri,and 83.00% accuracy of 2 years old A.gueldenstaedtii,but only 58.00% accuracy of 3 years old A.schrenkii.Gonads of 2 or 3 years old A.baeri were found at Ⅱ-Ⅲstages based on the ultrasonic images.Therefore,ultrasonography is a non-invasive method which is worth to apply in sex determination of young sturgeon.