The effects of equivalence ratio (RER) and steam/biomass (S/B) ratio on gasification performances such as temperature distribution, gas composition and gasification stability were investigated in a pilot-scale fluidized bed gasifier with different feedstocks (sawdust, rice husk, wood pellet and straw pellet). The results showed that typical product gas percentage components from gasification were as follows: H2 27.1%～30.4%, CO 29.7%～32.6%, CO2 25.3%～27.9%, CH4 4.9%～5.8%. The uniformity of temperature distribution increased with RER and S/B ratio. More uniform temperature distribution was obtained in the case of sawdust and rice husk gasification. In the downstream direction of the dense phase zone, H2 and CO increased significantly whereas CO2 and O2 decreased considerably. In the dilute phase zone, the components of product gas varted slightly. Increasing the moisture content of sawdust will deteriorate the gasification stability. An abrupt increase of temperature in the bottom of gasifier was observed during the rice husk gasification. A consistent increase of temperature drop and pressure drop was observed in the dense phase zone in the case of wood pellet and straw pellet gasification.