Cross-enterprise cooperative office method, device and system

The invention provides a cross-enterprise cooperative office method, device and system. The cross-enterprise cooperative office method, carried out at a request end, comprises the following flows: sending a friendship request to a receiving end to allow the receiving end to decide whether to accept cooperative office with the request end; when the receiving end accepts cooperative office with the request end, establishing a friendly enterprise relationship between the request end and the receiving end; and adding accounts for allowing cooperative office with the receiving end and setting the authority levels of the accounts to allow collaboration personnel logging on the accounts having different authority levels to refer to files in the corresponding levels through a working platform, thereby realizing efficient cooperation between enterprises having business contact.