Abstract: The current investigation followed by biomass based power plant for electricity generation.The Prosopis juliflora was selected as fuel for down draft gasifier.Properties of Prosopis juliflora were determined to check the feasibility of fuel.Characterization of producer gas was done by determining the different constituent，calorific value，density and tar content of producer gas.Performance evaluation of gasifier was carried out by observing the parameters like fuel consumption，specific fuel consumption，equivalence ratio，specific gas production rate，specific gasification rate and gasification efficiency.The volumetric percentage of carbon monoxide（CO），hydrogen（H2），carbon dioxide（CO2），methane（CH4）and nitrogen（N2）at 20 kW was 18.4%，13.8%，11.1%，2.40% and 54.2%，respectively.The calorific value，density and tar of producer gas varied from 4.17 to 4.85 MJm3，1.16 to 1.56 kgm3 and 10.2 to 10.0 mgm3 respectively with the increase of load from 5 to 20 kW.The biomass consumption rate，specific biomass consumption rate，specific gasification rate，specific gas production rate，equivalence ratio and gasification efficiency varied from 11 to 28 kgh，2.20 to 1.40 kg（kW·h），29.63 to 75.43 kg （m2·h），103.7 to 257.43 m3（h·m2） ，0.32 to 0.47 and 79.26% to 89.90% as the engine load increased from 5 to 20 kW.