Based on the MOD16 evapotranspiration (ET) data during the period of 2000—2013 and the vegetation type, the mathematical-statistics methods of Theil-Sen median trend, Mann-Kendall test and Hurst index were used to analyze the characteristics of temporal-spatial dynamic changes of ET and its future trend in Beibu Gulf coastal zone. The results showed regarding temporal variations, the annual ET of coastline in Beibu Gulf increased with a fluctuation rate of 1.41 mm/a in the study area from 2000 to 2013, and it was higher than that in the southern area of Guangxi. The trends of ET changing rate in east coast were faster than that of the whole region, while it was slower in the hilly areas and west coastal regions than that of the whole region. The order of increasing rate of seasonal ET was summer (111.88 mm) > autumn (93.45 mm) > spring (85.57 mm) > winter (47.98 mm), which accounted for 33.01%，27.58%, 25.25% and 14.16% of annual ET, respectively. Regarding spatial distribution, the spatial distribution of averaged annual ET in northeast-southwest centerline showed it was higher in the western coastal zone than that in the east, and the annual ET in southeast region reached minimum and the law of ETs Theil-Sen median trend was from -50.93 mm/a to 51.76 mm/a, the spatial distribution of ET showed a decreasing trend in coastal zone. Regarding the volatility of ET, the variable coefficient of ET was larger and its value was from 0.02~0.39. The ET in central and southeastern coastal zone presented a high volatility level, while the west and northwest of the coastal zone were in a low-volatility state, and the ET in Hepu County of Nanliu River Delta showed the maximum volatility. Regarding the future trend of ET, the Hurst index of ET was changed from 0.25 to 0.93, with a mean of 0.68, presented the right unimodal distribution. And the anti-sustained sequence (7.58%) was smaller than sustained sequence (92.42%), which indicated that the overall ET would take on an ongoing decreasing trend in the future.