The present invention belongs to the field of vehicle information acquisition and processing, and discloses a maintenance decision system and method for a maintenance period of operating vehicles. The maintenance decision system comprises an information input module, a control module, an information acquisition module, an information storage module, an information processing module, a result displaying module and an operating vehicle maintenance record service platform. The output end of the information input module is connected with the input end of the control module unidirectionally; the first output end of the control module is connected with the input end of the information acquisition module bi-directionally; the output end of the information acquisition module is connected with the input end of the operating vehicle maintenance record service platform bi-directionally; the second output end of the control module is connected with the input end of the data storage module bi-directionally; the third output end of the control module is connected with the input end of the information processing module bi-directionally; and the fourth output end of the control module is connected with the input end of the result displaying module unidirectionally. According to the method and system disclosed by the present invention, the objective and accurate evaluation on the maintenance cycle of the operating vehicles is realized.