The impact of plant density on qualitative and quantitative characteristics of fennel in a field factorial test with eight fertilizer factors of Nitrogen (50, 100 and 150), Compost (5 and 10 tons/acre), Nitroxin (20 and 40. Ml per liter) and control (without fertilizer); in addition to the variable of plant density (10 and 7 plants per square meter) was discussed based on random complete block design with four replications. Results of analysis of variance indicated that the impact of plant density was significant on plant height, number of umbels, seed yield, oil yield, harvest index and oil. In addition, mean comparisons showed that the highest performance was seen in application of 100Kg/acre of Nitrogen fertilizer in conjunction with the plant density of 40 plants/m2.