Abstract: With the aim of study characteristics of biomass pyrolysis in molten salt, experimental studies on characteristics of biomass pyrolysis in molten salt were carried out in a self-designed reactor. Effects of pyrolysis temperature, FeCl2 addition quantity in ZnCl2-KCl(with mole ratio 7/6) and biomass material on pyrolysis behavior of biomass were investigated. Pysical properties of bio-oil were measured, and main compositions of bio-oil were analysised by GC-MS. Pyrolysis process greatly depended on temperature and the yield of bio-oil increased at first and then decreased with the increasing of temperature. While the FeCl2 addition quantity was 5%, the best pyrolysis temperatures of rice straw was about 525℃, and bio-oil yield relatively high, could reach 18%, respectively. FeCl2 addition in molten salt could increase bio-oil yield. Water content of bio-oil produced from cellulose was much less than that from rice straw. Bio-oil was a kind of liquid with high water content and low ash, and its density was close to water, and viscosity was bigger than water, pH value was between 2.5 and 3.0. Components of bio-oil were very complexity, while methoxy group was relatively high. Bio-oil need to be refined before application. The research provides a scientific reference for production of bio-oil with molten salt.