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Assess the trend of rainfall change in Phu Quoc island is an interesting topic which establishes a scientific basis for rainfall forecast trends as well as regional development planning. Rainfall measurement data from 1985 to 2018 was used to analyse with different methods included Sen’s slope, linear regression, Mann-Kendall (MK) test, CV coefficient (Coefficient of Variation), PCI (Precipitation Concentration Index); examine drought level over time by using SPI - standardized rainfall index. Results show that, according to the linear regression analysis, regional annual rainfall is not much fluctuated, the rainy season and annual rainfall tend to decrease, while rainfall in the dry season tends to increase. According to Sen’s slope chart, July rain gains highest increasement, while that of August tends to decrease most. In general, the precipitation concentration index revealed the presence of a high and very high concentration of rainfall.
 K. E. Trenberth, L. Smith, T. Qian, A. Dai, J. Fasullo, Estimates of the Global Water Budget and Its Annual Cycle Using Observational and Model Data, Journal of Hydrometeorology, Vol. 8, Iss. 4, 2007, pp. 758-769, https://doi.org/10.1175/JHM600.1
 A. Piticar, D. Ristoiu, Spatial Distribution and Temporal Variability of Precipitation in Northeastern Romania, Riscuri si Catastrophe, Nr. XII 13, Nr. 2, 2013, pp 35-46.
 A. Asfaw, B. Simane, A. Hassen, A. Bantider, Variability and Time Series Trend Analysis of Rainfall and Temperature in NorthCentral Ethiopia: A Case Study in Woleka Sub-basin, Weather and Climate Extremes, Vol 19, 2018, pp. 29-41, https://doi.org/10.1016/j.wace.2017.12.002.
 A. E. Lawin, N. R. Hounguè, C. A. Biaou, D. F. Badou, Statistical Analysis of Recent and Future Rainfall and Temperature Variability in the Mono River Watershed (Benin, Togo), Climate, Vol. 7, Iss. 1, 2019, article 8, https://doi.org/10.3390/cli7010008.
 V. T. Hanh, C. T. T Huong, P. V. Tan, Trend of Maximum Daily Rainfall in Vietnam During 1961-2007, VNU Journal of Science, Natural Sciences and Technology, Vol. 25, No. 3S, 2009, pp. 423-430 (in Vietnamese).
 L. N. Quan, P. V. Tan, Projected Changes of Heavy Rainfall Indices over Vietnam Using Regional Climate Model (RegCM3), VNU Journal of Science, Natural Sciences and Technology, Vol. 27, No. 1S, 2011, pp. 200-210 (in Vietnamese).
 N. V. Tin, Non-parametric MK Test for Trend Detection of Maximum Short Period Rainfall Data in Ho Chi Minh City from 1971-2016, Vietnam Journal of Hydrometeorology, Vol. 683, 2017, pp. 52-55 (in Vietnamese).
 P. T. Long, N. V. Tin, Non-parametric Mann-Kendall Test for Trend Detection of the Start and End of Rainy Season in Mekong Delta, Vietnam, Journal of Climate Change Science, No. 7, 2018, pp. 1-7 (in Vietnamese).
 N. D. Thanh, P. V. Tan, Non-parametric Test for Trend Detection of Some Meteorological Elements for the Period 1961-2007, VNU Journal of Science, Natural Sciences and Technology, Vol. 28, No. 3S, 2012, pp. 129-135 (in Vietnamese).
 W. Hare, Assessment of Knowledge on Impacts of Climate Change, Contribution to the Specification of Art, 2 of the UNFCCC, WBGU, Berlin Germany, 2003.
 M. D. Luis, J. C. G. Hidalgo, M. Brunetti, L. A. Longares, Precipitation Concentration Changes in Spain 1946-2005, Nat. Hazards Earth Syst. Sci., Vol. 11, Iss. 5, 2011, pp. 1259-1265, https://doi.org/10.5194/nhess-11-1259-2011.
 J. E. Oliver, Monthly Precipitation Distribution: A Comparative Index, The Professional Geographer, Vol. 32, Iss. 3, 1980, pp. 300-309, https://doi.org/ 10.1111/j.0033-0124.1980.00300.x.
 P. K. Sen, Estimates of the Regression Coefficient Based on Kendall’s Tau, Journal of the American Statistical Association, Vol. 63, Iss. 324, 1968, pp. 1379-1389, https://doi.org/10.1080/01621459.1968.10480934.
 K. E. Trenberth, J. M. Caron, The Southern Oscillation Revisited: Sea Level Pressures, Surface Temperature and Precipitation, Journal of Climate, Vol. 13, Iss. 24, 2000, pp. 4358-4365, https://doi.org/10.11751520-0442(2000)013<4358:TSORSL>2.0.CO;2.