Abstract: This study utilized Japanese medaka (Oryzias latipes) as a model organism to evaluate the effects of microplastics (MP) on triclosan (TCS)-induced oxidative stress and reproductive toxicity in fish. The results showed that MP reduced catalase levels in TCS-exposed O. latipes, increased lipid peroxidation in tissues, and further upregulated the expression of cyp1a and vtg while downregulating vasa expression in the liver. These changes led to histopathological damage in the liver, intestine, ovaries, and testes. The results help elucidate the role of MPs in modulating the effects of TCS and provide a scientific basis for assessing the ecological risks of aquatic pollution.