The present disclosure provides a method for transmitting a large object, after a server establishes a session with a client, the method includes: the server divides a pre-transmitted large object into data blocks, and transmits one by one in sequence acquired data blocks and their sizes to the client; the client determines whether a received data block is transmitted successfully, if the received data block is transmitted successfully, the data block is saved, and a current data block transmission success message is returned to the server; if the received data block is not transmitted successfully, an end session request message or a re-transmitting current data block request message is returned to the server; and the server transmits the corresponding data block and its size or ends the session according to the received messages. The present disclosure further provides a system for transmitting a large object. When there is an error in transmitting a data block of a large object, the method and the system in the present disclosure process it in advance, thus saving bandwidth resources.