Microbial facies of thrombolite and stromatolite were developed and reached to their maximum diversity after each world wide mass extinctions (biotic recovery time). In study, the Permo-Triassic successions were investigated in Kuhe- Dena and Kuhe-Surmeh areas, in order to obtain the microbial facies development at the P/T boundary in the Zagros Basin.The obtained data indicate different microbial communities in the Lower Kangan strata, where the mass-extinction has happened in the Zagros Basin, consisting of Kuhe- Dena and Kuhe-Surmeh successions. . The microbial facies is marked by co-existed organisms such as blue-green algae and small marine metazoans in both studied areas with the same conditions. The thrombolite facies is characterized by clotted fabric or mesoclot microscopic texture in which has been produced by the biogenic interaction during the biotic recovery time, indicating the mass extinction effects at the P/T boundary in the Zagros sedimentary Basin. However, it should be mentioned that the obtained evidence such as microbial facies suggest somehow different mass extinction effects in two the studied areas. On the other hand, the mass extinction phenomena was compared with the Alborz Mountain Ranges, Arabian pennensula, North America and Western Europe at the P/T boundary. This comparison indicates the same microbial facies development after extinction, or biotic recovery time.