Embodiments of the present invention disclose an optical module, a line card and an optical communications system, which are used to implement that the optical module is used on a line card of different service rates, so as to reduce a development cost. The optical module includes: more than two male sockets are disposed, where the more than two male sockets are configured to plug-connect to female sockets disposed on a line card, and the line card is a line card of various different service rates; and the more than two male sockets include at least one first male socket, where the first male socket is configured according to the Multisource Agreement (MSA) for a dense wavelength division multiplexing (DWDM) optical module of a 100G service rate.