Variable-stroke soot blowing method for reducing reheat steam temperature deviation of fossil power plant

The invention relates to a variable-stroke soot blowing method for reducing a reheat steam temperature deviation of a fossil power plant. The method is characterized by comprising the following steps of: reducing deposited soot of the outer pipe region of a first-level reheater through shortening the soot blowing stroke of a soot blower in the region of the first-level reheater when a larger steam temperature deviation between the inner pipe and the outer pipe of a second-level reheater outlet is existent, increasing the steam temperature of the outer pipe outlet of the first-level reheater, and indirectly increasing the steam temperature of the inner pipe of a second-level reheater by using the characteristics of crossover arrangement of the first-level reheater and the second-level reheater; and reducing the blown soot in the inner tube region of the first-level reheater, maintaining the deposited soot distribution invariable, and reducing the steam temperature of the inner tube of the first-level reheater