The present study tries to determine the effect of HARVEST interval (re-growth) on quantitative and qualitative traits of Jerusalem artichoke as a promising forage plant. For this purpose, it has conducted an experiment at the research farm of Animal Science Research Institute, Karaj, Iran between 2015 and 2016. The experiment is based on randomized complete block design with three replications and two observations, with its treatments being consisted of different times of HARVESTing forage intervals every two, three, and four months following emergence or regrowth in the first year and every one, two, three, and four months in the second one, in which there has been no replanting. The highest dry weight of leaf, stem, and total forage belongs to HARVEST intervals every two months. The highest crop growth rate, relative growth rate, and biomass duration have been observed in cutting intervals of three, four, and two months, respectively. In the second year, the highest amount of crude protein of total forage is obtained in the cutting interval of one month, with the maximum amount of total forage ADF belonging to cutting interval of four months. Generally, the best time for forage HARVEST occurs every two months due to high yield forage (2056 g/m2), leaf to stem ratio of 0. 53, crude protein of 12. 50%, water-soluble carbohydrates of 3. 89%, ADF of 32. 98%, and NDF of 46. 05% of the Jerusalem artichoke.