A channel allocation method for radio data calls having different bandwidths to each other in a radio data call processing structure between a mobile switching system and an IWF is disclosed. The method includes receiving a data call connection request; allocating an available time slot and an E1 link; judging a requested bandwidth on the basis of a service option of a received data call; defining a weight value of each data call by using a rate of the requested bandwidth; and dynamically allocating an H.sub.0 channel on an E1 link on the basis of the number of data calls occupied at each H.sub.0 channel and the weight value of each data call.