The invention provides a method for increasing the hydrogen-carbon ratio in coal synthesis gas based on a chemical chain hydrogen production technology. The method comprises the steps: hydrogen is produced through a chemical chain circulating technology which adopts Fe2O3 as a reactant to react with methane, water vapor and oxygen, and according to different demands of coal chemical product production, the hydrogen-carbon ratio in the coal synthesis gas generated through a water coal slurry reaction is increased. Compared with a traditional water gas transforming method, the purity of the hydrogen produced through the method is high, the hydrogen-carbon ratio of a synthesis gas product is easy to control, water gas transforming pollution and consumption of a large amount of water are avoided, meanwhile the solid reactant, namely the Fe2O3 can be reutilized, and thus continuous operating of a system is ensured.