Mangrove is a wetland woody plant community growing in the Intertidal zone of tropical and subtropical beaches. It plays an important role in purifying seawater, preventing waves and protecting embankments, fixing carbon and storing carbon, promoting siltation and land formation, and maintaining biodiversity.At present, the indoor laboratory research on the response of mangroves to environmental stress is carried out by artificial control, which ignores the growth habits of different mangrove species, and most studies focus on single stress. Through the combination of field growth and manual control, this paper aims to study the effects of salt and copper stress on 11 functional traits of three mangrove plants (Kandelia candel, Laguncularia racemosa and Bruguiear gymnorrhiza) in five periods (from June 2018 to August 2020). The effects of salt and copper stress on leaf functional traits of different tree species in different periods were studied by single factor and two-factor variance analysis, which could further answer the scientific problem of mangrove plant functional traits in response to single and combined stress of salt and copper. The results showed that the functional traits of the three mangrove plants were significantly different in different periods. With the increase of time, the carbon content and canopy height of the three plants showed an increasing trend, and other functional traits showed different trends due to different species. Compared with native mangrove plants (Kandelia candel and Bruguiear gymnorrhiza), the invasive alien species (Laguncularia racemosa) had a faster growth rate. Under different periods, Laguncularia racemosa had better salt tolerance than Kandelia candel and Bruguiear gymnorrhiza. The growth and development of the three species were not sensitive to copper stress. In most periods, the single salt stress had no significant effect on plant functional traits (P < 0.05), but had significant effects on carbon content, canopy height, and specific leaf area (P < 0.05). Single copper stress had no significant effect on most functional traits of the three species. In addition, salt-copper combined stress had significant effects on leaf carbon, phosphorus, nitrogen-phosphorus ratio, and canopy height of Kandelia candel (P < 0.05), and had significant effects on leaf carbon, copper content, canopy height, and specific leaf area of Laguncularia racemosa (P < 0.05 ), while the salt-copper combined stress only had significant effects on SPAD value of Bruguiear gymnorrhiza (P < 0.05 ). In the protection and restoration of mangroves, the research results can provide a theoretical basis for interpretation of the causes and mechanisms of mangrove degradation, the monitoring and evaluation of mangrove growth, habitat management, and tree species selection.