Disclosed is a channel allocation method for asynchronous mobile communication system for mapping a call between channels equally. The method converts at least a mobile phone connected to a channel having a high loading dose and then connects the mobile phone to a channel having a low loading dose, in case that a difference of a loading dose between channels is greater than a predetermined value after a loading dose of available respective channel is measured in a node B/RNC and a difference of loading doses between available respective channels is calculated in an asynchronous mobile communication system.