The invention relates to a railway signal comprehensive maintenance system and method based on an intelligent decision-making expert system. To establish an intelligent control and maintenance technology for signal repair and maintenance under a long and large dense tunnel group condition of a high-speed railway is extremely urgent. The railway signal comprehensive maintenance system takes a high-speed railway signal system as the basis; an indoor microcomputer monitoring system is used for realizing acquisition of indoor equipment state information, and an intelligent AGENT unit is used for acquiring voltage and current of outdoor signal equipment in real time; and finally, acquired equipment information is recorded into each grade of database server, and fault information of an expert knowledge base is used for carrying out comparing judgment or pre-judgment or for providing a fault solution fed back to each grade of intelligent display terminal to guide signal maintainers to carry out fault processing. According to the railway signal comprehensive maintenance system, the risks that the system loses efficacy under the influence of manual factors or equipment, environment and other factors in a full life circle process of the signal system are reduced; and the working performance of the signal system is effectively improved, the faults are reduced and the operation risks are reduced.