NOVELTY - Thermochemical conversion of microalgae preparing bio-oil fuel comprises drying and crushing microalgae; weighing processed micro fine particles in high pressure reaction kettle, adding water, ethylene glycol, methanol, ethanol, n-propanol, isopropanol, acetone, ethyl acetate, 1,4-dioxane, tetrahydronaphthalenes, benzene, not adding catalyst, sealing, putting molten salt in selected solvent/algae, reacting, cooling; and extracting organic solvent, separating and filtering organic phase to obtain solid residue, distilling to remove organic solvent.    USE - Thermochemical conversion of microalgae preparing bio-oil fuel.    ADVANTAGE - The bio-oil obtained is brownish black thick liquid with yield rate of 9.8-64.6 wt.%, main components are: higher ethyl ester, olefin, aldehyde and amide; elemental composition and heat value are: 60.0-75 wt.% carbon, 7.0-9.0 wt.% hydrogen, 25- 10 wt.% oxygen, 8.0-2.0 wt.% nitrogen, 0.1-2.0 wt.% sulfur, and heat value is 25.0-37.0 MJ/kg. The raw material microalgae has high photosynthesis efficiency, strong adaptive capacity to environment, short growth cycle, low energy consumption, and easy for large-scale cultivation.    DETAILED DESCRIPTION - Thermochemical conversion of microalgae preparing bio-oil fuel comprises:    (A) drying and crushing micro-algae, sieving to drain to obtain microalgae fine particle;    (B) weighing processed micro fine particles in high pressure reaction kettle, adding water, ethylene glycol, methanol, ethanol, n-propanol, isopropanol, acetone, ethyl acetate, 1,4-dioxane, tetrahydronaphthalenes, benzene, not adding catalyst, sealing, putting molten salt in selected solvent/algae (volume/mass) at 2:2.5-16:2.5, and reacting for 5-120 minutes, controlling temperature at 170-370 degrees C, after reaction, cooling, opening production valve test gas, opening reaction kettle reaction mixture; and    (C) extracting organic solvent for reaction mixture, separating and filtering organic phase to obtain solid residue, distilling to remove organic solvent to obtain bio-oil, where organic solvent is low-polarity solvent.