Abstract: 【Objective】 To analyze the structure of the central element protein 3 gene（syce3） of synaptonemal complex in Mastacembelus armatus and investigate its expression characteristics, cellular localization across different sexes, tissues, embryonic development stages, and its response to temperature stress, thereby providing theoretical basis for sexcontrolled breeding of Mastacembelus armatus. 【Method】 In this study, the syce3 gene was cloned, and the physicochemical properties, structural and prediction of functional sites and phylogenetic analysis of syce3 were performed by bioinformatics. The expression of syce3 gene in 11 tissues was detected by real-time fluorescence quantitative PCR. And its expression in gonads was detected by fluorescence in situ hybridization. The effects of temperature on embryonic development and syce3 gene expression were also analyzed. 【Result】 The syce3 gene of Mastacembelus armatus was successfully sequenced, it comprised 303 bp and encoded 87 amino acid residues. The molecular weight of the syce3 protein was 10.03334 kD, with an isoelectric point（pI） of 4.85. The average hydrophilicity coefficient（GRAVY） was-0.609, indicating that syce3 was a hydrophilic protein. Secondary structure prediction revealed that syce3 consisted of 63.22% α-helices, 29.88% random coils, and 6.90% extended strands. Homology analysis showed low amino acid sequence similarity between Mastacembelus armatus syce3 protein with other species. Phylogenetic analysis further indicated that the nucleotide sequence of syce3 gene of Mastacembelus armatus was not closely related to other species. Real-time fluorescence quantitative PCR results indicated that syce3 gene expressed across all 11 tissues, with the highest relative expression in gonads—particularly in testes. Fluorescence in situ hybridization confirmed that syce3 gene localization in spermatogonia, spermatocytes, spermatids and sperm within testes, as well as in cortical follicular cells of ovaries. Temperature incubation experiments revealed that the relative expression level of syce3 gene at the cleavage stage at 26 ℃ was significantly higher than that at other embryonic development stages（P＜0.05）, and the relative expression level of syce3 gene at 26 ℃ was higher than that at 32 ℃. 【Conclusion】 The syce3 gene is successfully cloned and identified in Mastacembelus armatus, which is exhibited expression in spermatogonia, spermatocytes, spermatids, and sperm. It involves in early embryonic development and gonadal differentiation regulation of Mastacembelus armatus.