NOVELTY - Preparing biological aviation fuel comprises filtering Cornus wilsoniana oil, adding it into softened water, taking and drying the supernatant to obtain refined oil, subjecting the oil to hydrodeoxygenation reaction, contacting the refined oil with a hydrodeoxygenation catalyst, producing normal alkane, then guiding the normal alkane into a fixed bed isomerization reaction device, continuously introducing hydrogen into the device, performing isomerization reaction, condensing the gas-liquid mixture, and collecting, distilling and refining the liquid phase product.    USE - The method is useful for preparing biological aviation fuel from Cornus wilsoniana oil (claimed).    ADVANTAGE - The biological aviation fuel does not contain sulfur or aromatic hydrocarbon, and is good in quality, high in cleanness and environment-friendly.    DETAILED DESCRIPTION - Preparing biological aviation fuel comprises filtering Cornus wilsoniana oil for removing granular impurities at 60-70 degrees C, adding it into softened water with the same temperature, where a weight of the added softened water is 2-4% of the weight of the Cornus wilsoniana oil, stirring the mixture for 25-35 minutes, centrifugally treating the oil for 25-35 minutes at a speed of 2500-3500 revolution per minute, taking the supernatant and drying the supernatant for 2-4 hours in a vacuum drying oven at 102-105 degrees C for obtaining refined Cornus wilsoniana oil, cooling and guiding the refined Cornus wilsoniana oil into a fixed bed hydrogenation reaction device filled with a hydrodeoxygenation catalyst for subjecting the oil to hydrodeoxygenation reaction, where the filling capacity of the hydrodeoxygenation catalyst is 1-10% of the weight of the refined Cornus wilsoniana oil, continuously introducing hydrogen into the fixed bed hydrogenation reaction device until the hydrogen/oil volume ratio is 500-2000, controlling an absolute pressure to be 1-10 MPa, a temperature to be 250-400 degrees C and a liquid hourly space velocity to be 1-5 h-1, contacting the refined Cornus wilsoniana oil with the hydrodeoxygenation catalyst for removing the oxygen in the raw material, subjecting an unsaturated part of normal alkane and olefin to hydrogenation saturation for producing normal alkane, collecting and cooling the normal alkane, then guiding the normal alkane into a fixed bed isomerization reaction device filled with an isomerization catalyst, where the filling capacity of the isomerization catalyst is 1-10% of the weight of the refined Cornus wilsoniana oil, continuously introducing hydrogen into the device such that the volume ratio of the hydrogen to the oil is 500-2000 under the conditions of temperature of 200-350 degrees C, absolute pressure of 1-5 MPa and liquid hourly space velocity of 1-5 h-1, contacting the hydrogen with the isomerization catalyst for performing isomerization reaction, enabling the crude oil to produce small molecule normal alkaline and branched alkane, carbon dioxide, carbon monoxide and water for forming a gas-liquid mixture with hydrodeoxygenation and isomerization reaction, where the hydrodeoxygenation reaction comprises hydrodeoxygenation, decarboxylation and decarbonylation reaction, condensing the gas-liquid mixture by a condenser filled with normal temperature cooling water, collecting the liquid phase product, distilling the liquid phase product, collecting a fraction at 150-280 degrees C, and guiding the fraction into an oil refining device for refining the cut fraction in a highly clean manner for obtaining the biological aviation fuel.