Coal-based cities play an important role during urbanization. So it deserves a thorough study in the sustainable development for society and economy. This paper, based on the coal-based cities, establishes an index system for sustainable development, contrasts the approach degree of annual urban sastainable development with the relative optimizing value, quantizes via entropy theory the evaluated information and ranks the results in Jixi city from 1995 to 2000, fitting close to the factual situation.