Abstract: This paper studied the influence of the exogenous androgen on the gonad developmental process of female and intersexual Monopterus albus after being treated with large dosage of methyltestone(MT),by the method of gonad biopsy.We dissolved the exogenous androgen with salad oil,and then injected them into the abdominal cavity of female and intersexual Monopterus albus.The influence of the exogenous androgen on the gonad developmental process of the female and intersexual Monopterus albus was studied by light-microscope.The conclusion might lay the foundation for further revealing mystery of the sex-reversal,and we found some interesting structures in histology,although we could not get the sex-reversal male of Monopterus albus by inducing artificially.The results were as follows:① MT could promote the degradation of the oocyte of the female Monopterus albus,but it could not make the ovarian tissue of the female Monopterus albus degenerated completely.② MT could promote the enlargement and extension of the epigynum of the female and intersexual Monopterus albus,but it could not make the interstitial cells of the female and intersexual Monopterus albus proliferated.③ MT could promote the appearance of the "hollow lobules" on the epigynum of the female and intersexual Monopterus albus.These "hollow lobules" could be divided into two types,the Hollow lobule type Ⅰ("HL-Ⅰ") and the Hollow lobule type Ⅱ("HL-Ⅱ").And the Hollow lobule type Ⅱ may be the seminiferous lobules,which were produced under the abnormal development.④ MT could promote the development of male reproductive cells in the early period of the intersexual Monopterus albus.And it could even promote the excreting of male reproductive cells in seminiferous lobules in the late period of the intersexual Monopterus albus,with the emergence of the other type of the "Hollow lobule".⑤ The influence of MT on the gonad developmental process of the intersexual Monopterus albus was better than that of the female Monopterus albus.