Disclosed are a low congestion routing method of an Optical Network-on-Chip (ONoC) and related devices. In the method, a source IP node sends a route setup request to a first electrical router; the first electrical router determines a first target output port and sends the request to the destination IP node through the first target output port; the destination IP node generates an ACK packet and sends the ACK packet to a second electrical router; the second electrical router determines a second target output port and sends the ACK packet to the source IP node through the second target output port; the source IP node transmits the ACK packet to an optical transmission port, performs an E/O conversion on the ACK packet and sends an optical information packet through optical routers to the destination IP node; the destination IP node performs an O/E conversion on the optical information packet.