Abstarct: Mashhad-Chenaran plain is one of the most important plains of Khorasan Razavi Which is surrounded by two zones of Binalood (west and south west) and Kope-Dagh (north and north east). Qanat is a very valuable way to supply water for drinking and agriculture in this area. Therefore, the aim of this research is to evaluate the hydrogeological and hydrochemical properties of some selected Qanats in Mashhad-Chenaran plain. For this purpose, the discharge time series of Qanats has been investigated over a period of 50 Year (1340-1391). The qualitative properties of Qanats have also been evaluated through the collecting chemical analysis 21 samples of water. The results show that the general trend of groundwater level in the mashhad aquifer baxsed on the unit hydrograph of the aquifer is decreasing and the highest drop in this aquifer has occurred in the western margin. Changes in discharge of the Qanats during the 50-year period are divided into two parts: the baxse period (from the beginning of the statistical period until the adoption of the fair distribution of water law in 1361) and current period (after the adoption of the law on the determination of active agriculture wells without a license for exploitation in1380 until the end of the statistical period). The result of this two study periods indicate that there is a decreasing in discharge of Qanats with time. Evaluation of effective factors on decreasing discharge indicates the relationship between precipitation and discharge until the beginning of the current period. Changes in discharge during the current period show slight fluctuations with precipitation. Evaluation of discharge fluctuations and water table decreasing indicate that the most influence was related to the Qanats which located in middle zone of aquifer and this is because of well withdrawal. Investigation of the influence of Qanats morphological parameters and discharge show that the largest reduction of discharge in Qanats have occurred in Qanats with the lowest depth of mother well and length of the catchment area. On the basis of qualitative diagrams, the Qanats can be divided into carbonate and sulfate groups. All Qanats have appropriate quality for agriculture.