The utility model discloses an improved chain-grate heating furnace, which can be used for various works, such as the heating, the annealing, the drying, etc. and have a bi-directional regulating mechanism for regulating the spacing of the chain wheel. The front end is regulated by a screw thread pair, and the back end is regulated by feed screw nuts; the back regulation can be regulated to the optimum state in continuous production at any moment under the condition of no shutdown and non interference. A drum shaft has the self-regulated function. The utility model has the advantages of energy saving, high efficiency, convenience, and reliability.