To address the issue of low soil nutrients and low crop yields in coastal alkaline salines, a field experiment of straw combined with plastic film mulching in coastal alkaline salines was conducted in this study to explore the effects of different treatments on soil nutrients, enzyme activities and maize yield. Four treatments, including no mulching (NM), straw mulching (SM), plastic film mulching (PM), and straw mulching combined with plastic film mulching (SP), were set up during 2019-2020. In the 0-20 cm soil layer, compared with NM, the soil organic carbon (SOC) and soil catalase activity (SCA) of SM significantly increased by 23.4% and 46.2%, respectively (P < 0.05). The soil total nitrogen (STN), soil available phosphorus (SAP), available potassium (SAK), sucrase activity, urease activity, alkaline phosphatase activity, and maize yield (MY) of SP significantly increased by 40.7, 26.8, 13.9, 34.6, 73.8, 36.2 and 19.0%, respectively (P < 0.05). SOC, STN, SAP, SAK and SCA were significantly correlated with MY. Therefore, straw mulching combined with plastic film mulching has the best effect on increasing soil nutrients, soil enzyme activity, and maize yield and is suitable for promotion and application in coastal alkaline salines.