In order to evaluate the physiological and biochemical characteristics of rapeseed (Brassica napus L) cultivars in terms of irrigation interruption and delay planting date، an experiment was implemented in two crop years as a factorial split-plot in the form of a randomized complete block design with three replications in Karaj region. In the present study، irrigation in two levels including normal irrigation (80 mm evaporation from Class A evaporation pan) and irrigation cut-off from the stage of sowing and pod formation stages in two levels including Sep، 26 and Oct، 26 was placed in main plot and four winter rapeseed cultivars including Tassilo، Elvise، Neptune and Okapi were placed in subplots. According to the results، the highest content of chlorophyll in both planting dates (Sep. 26 and Oct. 26، respectively، with values of 1.59 and 1.88 mg. g-1 FW) and under normal irrigation conditions belonged to Elvise cultivar. The results showed that irrigation cut-off reduced the relative water content of leaves and increased leaf proline، soluble protein content and soluble carbohydrate content. Elvise and Neptune cultivars had the highest grain yield under normal irrigation conditions with 3346 and 3220 kg / ha، respectively، and under irrigation cut-off conditions، with a mean of 3211 and 3081 kg / ha، respectively. According to the Stress Tolerance Index (STI)، Elvise cultivar was identified as the most tolerant cultivar under dehydration stress in the pod formation stage onwards.