The invention relates to a fish gonad determination method. Said method includes the following steps: placing the fish to be examined into an electric anesthetization tank, adopting 25-30 V low-voltage dierct current to apply said direct current to fish the make electric anesthetization, then using an endoscope specially-design for fish and inserting it into genital operature and making dynamic determination from uterine tube/deferent duct to two sides or ovary/testis to obtain determinal data, then utilizing the gonadal development index parameters of different development stages of fish and determined gondal development condition to make male and female identification.