To investigate mangroves of different land use types in Nansha county, China, we analyzed the corresponding N₂O and CH₄ emissions, water temperature, salinity, acidity and alkalinity, dissolved oxygen, redox potential, nitrate, nitrite, ammonia nitrogen, and organic matter at five sites. The removal rates of NO₂⁻, NO₃⁻, and NH₄⁺ in mangrove wetlands were 43.6%, 41.2%, and 65.0%; however, CH₄ and N₂O emissions of mangrove affected by shrimp ponds are 2–3 times and 3–9 times more high than other wetlands. These results showed that, although mangrove wetlands can significantly reduce N, P, and other nutrient elements in shrimp pond wastewater, they can also significantly increase N₂O and CH₄ emissions. This indicates that mangrove wetlands should be used with caution for the treatment of shrimp pond wastewater.