A pilot study was conducted on a seawater desalination system using an air flotation–ultrafiltration–reverse osmosis process to address operational challenges posed by fluctuations in inlet water temperature. During the field test, the seawater temperature increased gradually from 3 ℃ to 13 ℃, and the average turbidity of the raw seawater inlet was approximately 7 NTU. The results showed that the turbidity of the air-flotation effluent remained below 3 NTU, while the turbidity of the ultrafiltration effluent was maintained below 0.3 NTU, indicating stable performance of the pretreatment system. Operating at a recovery rate of 40%, the reverse osmosis membrane flux rose from 8.9 L/(m²·h) to 14.7 L/(m²·h), and the system operated steadily as the inlet pressure decreased with rising temperature.