The present invention relates to the field of communications technologies and provides an optical module and an optical network system. A first chip is arranged on a lower cover plate, an upper cladding, which is close to a first PD, of the first chip is covered by a first upper cover plate; a first dividing groove divides the first chip into two parts, and a WDM and a light blocking material are arranged inside the first dividing groove, so as to block stray light transmitted inside the upper cladding, a sandwich layer, a lower cladding, and a base of the first chip; and a light blocking material is arranged on a side of the first upper cover plate facing the first LD, so as to block stray light transmitted on a surface of the first chip, thereby blocking the stray light that enters the first PD, and significantly reducing crosstalk of the optical module. Further, the PLC optical module has a simple structure, and therefore is easy to manufacture at a low cost.