New materials and equipment according to the combustible fraction of diesel miscible flammable characteristics of biomass tar was analyzed. Diesel engine fueled with different proportions of combustible biomass tar distillates and diesel miscible oil power performance was proposed. Experimental results showed that biomass tar combustible miscible distillate and diesel oil had good power and economy. When the power of agricultural diesel was low, the consumption of miscible oil sample was less than diesel. When the power of agricultural diesel was high, the consumption of miscible oil was less than diesel with the replacement ratio of 10% in diesel, but higher than diesel with replacement ratio of 20%. The maximum power of agricultural diesel engine with miscible oil was higher than the rated power of the agricultural diesel engines which met the power requirements of agricultural diesel engines.