The symbiosis of mycorrhizal fungi with plant roots is one of the most important symbiotic relationships in soil. In this study, biodiversity and symbiosis of arbuscular mycorrhizal fungi (AMF) with Amygdalus arabica Olivier, A. lycioides Spach, A. elaeagnifolia Spach and A. orientalis Mill. were investigated in three sites in Ilam province. After extracting soil samples from a depth of 0-30 cm, spores of mycorrhizal fungi were separated by the wet sieving method and the fungi were identified based on the morphological characteristics of the spores. The results revealed 34 different species of AMF belonging to 10 different genera. The highest biodiversity of fungi (28 species) was observed in A. arabica. In addition, 19 AMF species in A. elaeagnifolia, 25 in A. orientalis and 26 in A. Lycioides were identified. Moreover, the lomus with 49% and G. nanolumen with 21% were of the highest relative frequency of AMF genus and species among all the tree species, respectively. Significant differences were observed between Amygdalus species in terms of spore density, species richness and Shannon–Wiener diversity index of AMF. So that most of the three indices were observed in A. arabica. Also, spore density showed a negative correlation with soil sand percentage and phosphorus amount, as well as a positive correlation with soil clay percentage.