In this study the biotic and abiotic characteristics of Ardalan dam reservoir was studied from 2011 to 2012. Diatoms, Bacillariophyta, was the main phylum of phytoplankton in Ardalan dam reservoir that was dominant in the most seasons and green algae, Chlorophyta, was the second dominance groups. Survey of zooplanktons showed there were 25 genus from 6 phylum, and Rotatoria constitute 64% of the zooplanktons in. The average phytoplankton and zooplankton abundance during this study were about 19.15×106 and 1863 per liter of lake water respectively. Survey of benthic communities showed that Chironomidae and Tubificidae were the main benthic groups in Ardalan dam. Average of benthic biomass during this survey was 0.9 gr/m2 which is very poor. Sediments in Ardalan dam was mostly of silt and clay. Fish structure survey by gill nets in Ardalan dam showed that common carp and silver carp, by %53 and %45 respectively were the main economical species in the dam. Hydro chemical survey showed that total phosphorus and total nitrogen were 0.073 and 0.779 mg/L respectively. The amount of chlorophyll a was 6.03 mg/m3. The range `of dissolved oxygen was 6.4-10.5 mg/L. Average of EC was 576 µs/cm. Since the water temperature just in august month was more than 20ºC, the appropriate period for warm water fish culture in this reservoir is limited.