The rape straw was chosen as experiment materials, and different concentrations of La/MCM-41 were prepared by the impregnation method, then online upgrading of rape straw pyrolysis vapors was performed over La/MCM-41. The modified catalysts were characterized by XRD, SEM and Py-IR, respectively. The influence of the introduction of La on the physical and chemical characteristics of organic phase of bio-oil was analyzed. The results showed that La/MCM-41 had the standard MCM-41 structure and typically hexagonal ordered structure, the surface of La/MCM-41 had more acid of Bronsted acid sites and Lewis acid sites. The organic phase included a variety of organic compounds, such as acid, aldehyde, ketone, alcohols, hydrocarbons and others. The modified MCM-41 catalyst can effectively remove the acid, aldehyde and ketone contained in the biooil organic phase. At the same time, when the La was loaded up to 5%, the biooil organic phase achieved a high yield rate to 18.83% and better physciochemical properties. The heating value of organic phase was up to 33.69MJ/kg and the content of hydrocarbon was increased significantly to 34.59% and mainly with monocylic aromatics hydrocarbons, which reduced the content of oxygen in oxygenated compounds. The research result would provide the reliable theoretical basis and experimental basis for the efficient utilization of biomass and the further modification of MCM-41 molecular seive.