The special climate , terrain and environment circumstances is the leading causes to the uneven distribution of rainfall in time and space that easily result in the drought in the south -west Taiwan .The essay evaluated the tem-poral and spatial fluctuations of droughts in south -west Taiwan through the measurement of the rainfall abundance sta-tus by using the standardized precipitation index ( SPI) .Taking the hydrological data of 132 weather stations for analy-sis, supplemented by the drought historical events , it is identified the start , delay status and scope of the droughts , and established the drought grade severity limit to the various hydrological parameters so as to further discuss the drought monitoring capacity of the SPI .The study was conducted based on the data of 2002 and 2003 drought years . The result shows that the standardized precipitation index ( SPI ) can effectively and exactly illustrate the start of the drought , with obviously drought accumulative effect .By using the accumulated four months SPI , the evaluation result shows that the predicated drought space distribution is consistent to the historical drought events .Therefore , it is suit-able and reasonable to illustrate the drought events in the south -west Taiwan by the accumulative four months SPI .%台湾西南部地区因气候、地形、环境特殊，使降雨在时间与空间上分布不均，易发生干旱，本研究利用标准化降雨指标衡量降雨丰缺情况，评估西南部地区干旱时空变动特性。以132个气象站为分析对象，以水文数据为主，干旱历史事件为辅进行整理，确认干旱的起始、延时状况及范围，并建立各项水文参数的干旱等级界限值，进而探讨该指标干旱监测能力。本文以2002年及2003年干旱年为例进行研究，结果显示：标准化降雨指标可有效且准确地显示一场干旱的起始，具显著的干旱累积效应。利用累积4个月的标准化降雨作为评估指标，所预测出的干旱空间分布与历史干旱事件形态较为一致，因此以累积4个月的标准化降雨对西南部地区干旱事件进行描述是适当且合理的。
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