The invention discloses a method for logging in to a client side omitting password entering and supporting an SIP. The method comprises the steps that a mobile phone number is input, a login button is clicked, if it is the first time for a client to log in to the client side, the login can be directly carried out, if it is not the first time for the client to log in to the client side, information of the client is inquired through a server, a mobile phone of the client is called back, the client judges whether a new device is allowed to be bound up or not through information, if the client allows binding of the new device, the login is successful, and if the client rejects binding of the new device, the login fails. According to the method for logging in to the client side omitting password entering and supporting the SIP, the client side is directly bound with the mobile phone of the user, it is ensured that the user determines the login result under the condition that the mobile phone is replaced or illegal persons carry out hostile attack, the privacy of the user is protected to the maximum extent, user operation is reduced, and the login process is simplified; due to the fact that the client side is bound with the mobile phone of the user, safety is improved to the maximum extent, and when unique value validation fails, the client side can be bound with the mobile phone, a system carries out ringback on the mobile phone of the user, and the user can determine information accuracy.