Disclosed is a line card chassis including line card units, switch fabric units and optical fiber interface units. The switch fabric unit includes a switch fabric chip module, and an onboard optical assembly module for mutual conversion between an optical signal and electrical signal; an electrical signal interface of the onboard optical assembly module connects the switch fabric chip module having a switching and route-selecting function, and the switch fabric chip module connects a line card unit through an electrical connector; an optical signal interface of the onboard optical assembly module connects an optical fiber interface unit through an optical connector; the optical fiber interface unit couples the optical signal to a cluster interface on a router panel through an optical fiber; the cluster interface concatenates different chassis of the router. Also disclosed is a router applying the line card chassis, a route- selecting method, and a packet processing method.