Changes in land use caused by aquaculture, urban construction, and other factors have led to severe damage to mangrove ecosystems, posing a major threat to mangrove biodiversity. Understanding the community structure of fish in the Leizhou Peninsula mangroves and investigating the impact of human activities on the fish community structure are crucial for the conservation of mangrove fish resources. This study is based on fish data from 21 tidal creeks in seven mangrove areas of the Leizhou Peninsula from 2021 to 2022. Land use data in the surrounding areas were combined to study the relationship between fish community structure and land use types. The results show that a total of 49 fish species were collected and identified, belonging to 8 orders and 25 families. The order Perciformes had the highest number of fish species, with 33 species accounting for 75.5% of the total species. Among them, the family Gobiidae had the highest number of species, with 15 species accounting for 30.6%. In terms of diet, the main categories were omnivorous fish and carnivorous fish, accounting for 53.06% and 44.90%, respectively. The Shannon-Wiener diversity index of fish communities in different mangroves ranged from 0 to 2.5 in autumn, winter, and spring, while the Simpson diversity index ranged from 0 to 0.9. There were significant differences (P>0.05) in fish abundance, species richness, and biomass among the different mangroves. Except for the fish communities between Beitan and Liushawan mangroves in autumn, which showed no significant differences (P>0.05), the fish communities in the other mangroves differed significantly in all three seasons (P<0.05). Human activity intensity, mangrove area, and east-west coast had significant main effects and interaction effects on fish diversity index, abundance, species richness, and biomass (P<0.05). The abundance of omnivorous fish such as Acentrogobius viridipunctatus showed a positive correlation with the proportion of urban land, arable land, and forest land, while the abundance of carnivorous fish such as Ambassis gymnocephalus showed a negative correlation with the proportion of urban land, arable land, and forest land. The abundance of fish species such as Oreochromis niloticus showed a positive correlation with the proportion of fishpond area. The results of the study indicate that human activity has had a negative impact on fish community structure, and the rational planning of land use in the surrounding areas of mangroves can be an important means for the conservation and utilization of mangrove fish.