〔Abstract〕 To investigate the effect of polystyrene microplastics(PS-MPs) on myocardial injury in mice and its molecular mechanism. Methods A total of 60 male C57BL/6 mice were randomly divided into normal sa- line group , 0. 1 , 1 , 10 mg/kg PS-MPs exposed group , and doxorubicin [5 mg/( kg · w ) ] group treated for 8 weeks . After treatment , we measured blood pressure , cardiac organ coefficient , cardiac histopathological changes , oxidative stress markers reactive oxygen species ( ROS) , malondialdehyde ( MDA) , glutathione ( GSH) , 4 - hydroxynonenal (4-HNE) and nuclear factor E2-related factor 2 ( Nrf2) , serum centroid injury markers creatine kinase MB (CK-MB) and troponin ( cTnT) , ferroptosis marker recombinant glutathione peroxidase 4 ( GPX4) , Recombinant solute carrier family 7 (SLC7A11) as well as ferrous ions (Fe2 + ) . Results Compared with the neg- ative control group , vacuolation , inflammatory infiltration and collagen fiber deposition were evident in the hearts of mice after PS exposure . The levels of myocardial injury markers CK-MB and cTnT significantly increased . Cardiac organ coefficient decreased , blood pressure increased , oxidative stress markers and ferroptosis markers increased . Conclusion PS-MPs exposure can induce oxidative stress and activate ferroptosis pathway , resulting in myocardial injury in mice .