The vapors directly catalyzed from vacuum pyrolysis of rape straw was investigated over HZSM—5 in a two-stage fixed-bed reactor to determine the effects of operating parameters on the product yields, including catalyzing temperature, biomass to catalyst mass ratio, and catalyst Si/Al ratio. The optimization of the oil phase yield was further conducted by employing response surface methodology (RSM). The statistical analysis showed that the operating parameters significantly affected the product yields. The optimal conditions for the maximum oil phase yield were obtained at catalyzing temperature of 491.0℃, biomass to catalyst mass ratio of 0.301, and catalyst Si/Al ratio of 53. Confirmation runs gave 9.80% of oil phase yield compared with 9.90% of predicated value. The upgraded bio-oil consisted of separable oil and aqueous phases. The H/C molar ratio, pH value and higher heat value (HHV) of the oil phase were 1.518, 5.15 and 33.80MJ/kg, respectively. It showed that the oil phase had a higher yield and the qualities, which can be used as an engine fuel. The H/C molar ratio and HHV of the aqueous phase (dry basis) were 1.269 and 29.69MJ/kg, respectively. The aqueous phase also had a high fuel value. 