The sex and gonad development in cultured Acipenser baerii was scanned by ultrasonic scanning. The results of sex and development stages of scanned A. baerii were identified by Minimally Invasive Surgical technique and histological examination. By comparative study, the results showed that there was higher accuracy of sex identification in A. baerii by ultrasonic method, the accuracy of identification in female was 95% higher than that in male, which was 87%. Success of gonad development identification by ultrasonic method was decided by gonad development, the accuracy of gonad development in early stages (stages Ⅰ-Ⅱ) was 65.25% lower than that in later stages (stages Ⅲ-Ⅴ), which was 88.65%.The speed of sex identification using ultrasonic technology was faster, according to the developmental status of A. baerii， the duration time was only 30 s.