Abstract: The study on characteristics of black liquor from non-wood fiber chemical pulping process shows that it has high content of ash(silicates), pentoses and high viscosity which will influence the normal evaporation operation. The heat transfer capacity of non-wood pulping black liquor is poor and easy to form scales. At present, there are no normal evaporation installations which can be operated economically. An new type of evaporator is designed and installed both in the pilot scale and industrial scale. It proves that,due to presenting of effec rive evaporating space, the new designed horizontal spraying-film evaporator has extremely a high evaporating capacity, high heat-transfer coefficient, and easy foaming and scaling working mass as non-wood black liquor, etc. The mean of evaporation intensity for black liquor (from wheat straw pulping process) could reach up to 28～45 kg/(m2 ? h).