The present invention provides a method, device and system for verifying user communication number validity. The method is applied to a business platform providing service for a user which a user communication number to be verified belongs to. The method comprises: determining a communication operation platform which the user communication number to be verified belongs to according to the user communication number to be verified; sending query information to the query interface provided by a communication operation platform, and obtaining the current state information of the user communication number to be verified from the communication operation platform; and determining whether the service provided for the verified user communication number is valid or not according to the state information returned back from the communication operation platform. According to the invention, before merchants provide service for users, the merchants determine whether the user communication numbers are located at a valid state capable of providing service, and the service can be only provided for the users in the valid state; and moreover, through the mode, the problem is avoided that the merchants directly initiate verification and disturb the users, and the user experience of the products/business provided by the merchants is effectively improved.