Disclosed is a line card chassis which includes line card units, optical electrical conversion units and optical fiber interface units. The optical-electrical conversion unit has an onboard optical assembly module used for mutual conversion between an optical signal and an electrical signal; an electrical signal interface of the onboard optical assembly module is connected to the line card unit through an electrical connector, and an optical signal interface of the onboard optical assembly module is connected to the optical fiber interface unit through an optical connector; and the optical fiber interface unit couples the optical signal to a cluster interface of a panel on a router through an optical fiber, and the cluster interface is to concatenate different chassis in the router. Also disclosed is a multi-chassis cluster router and a packet processing method.