The invention provides a preparation method of high-matching coal-oil slurry. The preparation method comprises the following steps: carrying out coal washing, crushing and drying, and grinding the dried coal into coal powder; mixing the coal powder with heavy oil according to a certain ratio; and adding a catalyst, and carrying out stirring to prepare the coal-oil slurry. The coal meets the following requirements that the volatile content is larger than or equal to 37%, the hydrogen-carbon atom ratio is larger than or equal to 0.75, the inertinite content is less than or equal to 20%, and vitrinite reflectance is less than or equal to 0.65. The heavy oil meets the following requirements that the ash content is less than or equal to 1.0%, dynamic viscosity of the heavy oil at 100 DEG C is less than or equal to 1500 MPa, the hydrogen-carbon atomic ratio is 0.7-1.70, and the aromatic degree is greater than 0.20. The coal-oil slurry prepared by the method has high matching performance, andthe coal and heavy oil in the coal-oil slurry can be prevented from layering, so that the problem that coking is caused due to local overheating caused by the fact that the coal-oil slurry is deposited in a preheater or a reactor can be solved. Meanwhile, the synergistic effect between the coal and heavy oil can be fully exerted, the conversion rate and the oil yield of the coal and heavy oil areimproved, and therefore the method is more practical.