Our country with average precipitation of 250 mm is located in arid and semi-arid region, although the Northern regions receive an annual rainfall of about 200 mm but there are areas in the central parts of the country with the rainfall of less than 50 mm. Therefore, it is the necessary to pay more attention in political decisions to these regions. For a regional drought analysis in order to properly deal with this phenomenon and in order to reduce the damage caused by it-is essential to study drought from different angles. Monitoring, forecasting and analysis of national and regional drought, is usually used in its investigation. There are several indices for drought analysis among which the most common method is the Standardized Precipitation Index which is very acceptable to the international community. The indexes for drought zoning analysis are increasingly used in different regions. One of the important characteristics of flexible SPI index is its calculation for different time scales and different types of drought. It was criticized that the index in different time scales may confuse investigators and users on water resources to specific detect of the scales in a region. Multiple Standardized Precipitation Index (MSPI) has fixed this problem. In this study, this index was calculated for Isfahan province. The information requires monthly precipitation. By checking 29 climatology and synoptic stations in the region were selected. For MSPI calculation, SPI index in time scales 3-6, 6-12, 3-12, 12-24 and 24-48 month were calculated. Then on the scales, principal component analysis was performed for each station separately. After estimating the first principal component for index calculation (MSPI) they are standardized. For its evaluation, Standardized Precipitation Index (SPI) will be compared. If the time scale for an area is not known beforehand, this index can be used. The results showed that the best time scales in Isfahan to use this indicator index (SPI) are primarily timescale (12-24) months and the second could be timescale (6-12) months. Keywords: Priciple Component Analysis, Isfahan province, Multivariat Standardized Precipitation Index, Standardized Precipitation Index
