It is accepted that climate change has a great impact on water cycle and regional water balance，and thus it would change the formation and evolution of drought conditions in some degree．In this context，the standardized precipitation evapotranspiration index(SPEI)，which has also taken another important factor evapotranspiration in the process of regional water balance into consideration，would be more suitable for drought monitoring than the standardized precipitation index (SPI)．The different time scales SPEI can re-flect the duration informations of drought，so the single SPEI of a certain time scale can only indicate a fraction of drought information．In order to form an overall judgement in drought monitoring，a new index called joint drought index (JDI)was established by the combination with different SPEIs．The accuracy and effectiveness of JDI in drought monitoring were then verified by the forecast evaluation　system and comparison with the actual drought． In conclusion，JDI can be used as a new ideal index for future drought monitoring．