Reseach on LT-based communication between peers in BT system In this paper, we present a new communication protocol between peers in BitTorrent (BT) system based on the Luby-Transform (LT) code. Being different from standard BT, our protocol has three special strategies: peers transmitting coded block, REQUEST and PIECE messages processing that is based on the state of piece, and Rarest First algorithm taking uncompleted pieces into account. Then we simulate our protocol in peersim simulator. The results show that our system has a 26% increase on average in 50M-sized files compared with BT.