In order to assess the effects of different nitrogen fertilizer rates and planting date on yield and yield components of spring canola cultivars, an experiment was conducted in factorial split plot based on randomized complete blocks design with four replications at the experimental field of Gonbad-e-Kavous University during the growing season 2013-2014. Treatments experiment were included four canola cultivars (Hayola 401, Zarfam, Hayola 308 and RGS003), two planting date (Nov 11 and Dec 21) and three levels of nitrogen fertilizer (0, 75 kg/ha and 150 kg/ha). The results of variance analysis showed that planting date and nitrogen fertilizer had significant effect on yield and yield components. The means comparison demonstrated that with the increase in nitrogen fertilizer application in both planting date, number of grain per pod, number of pods per plant, 1000 grain weight and grain yield increased. Interactions effects showed that with nitrogen fertilizer rates increase, yield and yield components were improved significantly in each planting date. Canola cultivars showed significant difference with  respect to grain yield, and this  occurred in the highest fertilizer rate (100% fertilizer recommendation), appropriate planting date (Nov 11) and in three groups, high (RGS003), middle (Hayola 401 and Zarfam) and low yield production (Hayola 308).