The invention provides a communication number preprocessing method and device. Based on the request of the Internet service server, whether the communication number is a domestic communication number,whether the communication number is a mobile phone number and whether the communication number is an effective mobile phone number are sequentially judged, and the effective domestic mobile phone number can be identified, so that an operator side identifies whether the communication number is the effective mobile phone number; thus, the third-party internet service server can identify the effectiveness of the mobile phone number immediately, the situation that a user cannot use a new mobile phone number to register and receive a short message verification code is prevented, and the user experience is improved; moreover, when the mobile phone number of the user cannot be registered or the short message verification code cannot be normally received, the user can think the problem of the mobile phone number at the first time and try to solve the problem through the service provider customer service, so that the service provider customer service pressure is effectively reduced.