Fire is a common, destructive and catastrophic factor in many rangeland ecosystems, playing a crucial ecological role and affecting the diversity and composition of species. The Freizi mountain region, located in the northwest of the Binalud mountain range in northeastern Iran, has unique climatic and geographical features and provide a suitable habitat for various plant species.This research investigates the effects of fire on flora, life form, growth form, age class of plants, diversity and species richness. To investigate the occurrence of fire, the time since the last fire in each site was determined with guidance from experts and local people of Farizi region. Ecologically homogeneous sites were selected based on fire history: one site with a fire in the last two years, two sites with a fire in the last 11 and 21 years, and a control site (no fire) with similar ecological conditions.During the spring and summer growing seasons of 1401, two 50-meter long transects in the shape of the letter T (one along the length and one across the width of the range) were established at each site. Six one-square-meter plots were placed along each transect, resulting in 12 plots per site and a total of 48 plots. Floristic characteristics and indices of diversity and species richness were measured. A total of 68 plant species belonging to 19 genera were identified. Throphytes (36%) and hemicryptophytes (30%) were the dominant biological forms in this region, followed by chamophytes (15%) and phanrophytes (12%). The results of one-way analysis of variance showed that the time factor after the fire has significantly caused diversity changes among the sites. Diversity changes were highly correlated with time factor. The species richness was highest at the 11-year site, and slightly higher at the two-year site compared to the 21-year site. For the q1 index, the two-year and 21-year sites were similar, with the greatest variation at the 11- year site, indicating that variation is highest at medium time intervals. Long-term fires have increased the number of perennial forbs, shrubs, and shrubs. Therefore, according to the amount of rainfall and the ecological potential of the region, fire is recommended as an effective solution to improve the vegetation cover.