The invention discloses a method for comprehensively utilizing gasification slag resources. The method is characterized by comprising the following steps that (1), hydraulic classification is carriedout, a gasification slag is placed in a liquid phase, and a coarse slag and a fine slag are selected according to different particle sizes; (2), the coarse slag is treated and used as building materials, and the fine slag is ground; (3), thick liquid proportion is carried out, the fine slag after powder grinding is mixed with a chemical agent including a thick liquid adjusting agent, a capturing agent and a foaming agent to prepare a slag thick liquid with a certain concentration; (4), separation is carried out, slag thick liquid is separated into high-carbon powder and primary tail ash, the primary tail ash is re-separated into middle carbon powder and secondary tail ash; and (5), the high-carbon powder is treated and used for preparing a carbon-based material, the medium-carbon powder istreated and used as fuel, and the secondary tail ash is treated and used as building materials. According to the method, the high-calorific value carbon and the low-burning-loss tail ash in the gasification slag are efficiently separated, the utilization path of the gasification slag can be greatly improved, raw coal resources are saved, and the problem of the gasification slag pollution environment is effectively solved.