Experiments on evaporation of High-TDS phreatic water in arid area are rarely inrestigated in home and abrood. Experiments on evaporation of different TDS (3,0, 0,0 g/L) preatic water were carried out to research evaporation rule of High-TDS phreatic water in arid area. Results show that there is significant linear positive correlation between cumulative evaporation and time duration under the research condition, also the same relationship between TDS of phreatic water and cumulative salinity in soil profile. The variation of phreatic water evaporation is lag behind the change of surface measured by EФ20 equipment, but both of them are more drastic at nighttime than the daytime. Except the treatment of 3g/L TDS, the nighttime evaporation contribution to the whole day evaporation of phreatic water in other treatments achieved sixty percent. The research shows that the daytime evaporation capacity has significant effect on nighttime evaporation, and the soil water, vapor condense at profile also is an important driving factor for the nighttime evaporation.