Abstarct: Beauveria is a globally distributed genus of soil-borne entomopathogenic hyphomycetes of interest as a model system for the study of entomopathogenesis and the biological control of pest insects. Species recognition in Beauveria is difficult due to a lack of taxonomically informative morphology. This matter has prevented assessment of species diversity in this genus. In total, we have isolated 166 isolates of Beauveria from different location of Iran. These isolates were isolated with insect bait method. Molecular analyses were done baxsed on nuclear ribosomal internal transcribed spacer (ITS) sequences for thirty five isolates. baxsed on molecular characteristics, 29 isolates were identified as Beauveria bassiana, 3 isolates as B. amorpha, 1 isolate B. brongniartii, 1 isolate B. malawiensis and 1 isolate B. sungii. Phylogenetic trees were inferred using Neighbur-Joining method. Four well supported clades with compared Beauveria from anothers species. In this study, in order to find a more effective and safe biological control agent, we investigated different isolates of B. bassiana and tested their pathogenicity on Sitophilus oryzae, measure of growth rate and conidial production. For bioassays, Concentrations of conidia were calculated using a haemocytometer and adjusted to 1 × 108 viable conidi/ml. Isolate SHU.M.022 was the most pathogenic against S. oryzae, with 89.9 % mortality. Isolates SHU.M.018, SHU.M.163 and SHU.M.042 were the least pathogenic against S. oryzae, with 25 % mortality. Investigation of growth rate showed isolate SHU.M.068 with mean 18.28 ml/day was the most growth rate and the isolate SHU.M.023 was the least growth rate (4.31 ml/day). Examination of conidial production exihibit isolate SHU.M.156 with mean 37.83 × 106 conidi/ml was the most conidial production and the isolate SHU.M.015 with mean 4.417 conidi/ml was the least conidial production.