A loading method of a base station system in a digital cellular system. The loading method run in its own processor includes the steps of: requesting its upper processor to load a file, receiving a file header from the upper processor, and assigning a storage area corresponding to a size of the file header; transmitting a receiving completion signal indicating that the file header has been received to the upper processor, receiving file data from the upper processor, and storing the file data in the storage area; checking whether all the file data corresponding to the file size has been received; and if all the file data has been received, performing an operation by use of the file data received to run loading in its own processor.