Abstract: In order to distinguish the sex of Penaeus monodon at embryonic and early stages of postembryonic development, we collected the individuals of fertilized eggs, Nauplii larvae, Zoea larvae, Mysis larvae, PL1 (1 day post-larvae), PL30 (30 day post-larvae) and subadults, tracked them by an improved Insertion/Deletion (InDel) marker, then established the detection methods of sequencing and fluorescence quantitative PCR. The results indicate that a sex-specific sequences could be obtained by this method. The result of sex discriminating of subadult shrimps by sequencing method (accuracy rate of 100%) was consistent with that by external observation method. Sex-specific sequences could be amplified from the samples of fertilized eggs, Nauplii larvae, Zoea larvae, Mysis larvae and post-larvae. Furthermore, we explored a rapid discriminating method based on the melting curve of qRT-PCR (Quantitative real-time polymerase chain reaction) with SYBR Green, and the value of melting temperature (Tm) of sex-specific sequences was (79.10±0.10) ℃ for male and (78.45±0.20) ℃ for female. The sex of individuals of PL30, subadults and Nauplii lavae at Stage VI could be distinguished by the specific melting curve accurately, with an accuracy rate over 96.3%.