The invention discloses a triplexer wave splitter based on planar lightguide integration, belonging to the technical field of optical access network. The wave splitter is characterized in that an asymmetric Y branch wave guide structure is adopted to separate light with a wave length of 1310nm from light with a wave length of 1490nm and 1550nm; a directional coupling wave guide structure separates light with a wave length of 1490nm from light with a wave length of 1550nm. The beneficial effects of the invention are: the triplexer wave splitter based on planar lightguide integration can realize multiplexing/demultiplexing function of light with wave lengths of 1310nm, 1490nm and 1550nm and light wave within the scope of relative ITU-T stipulated band width, thus having the advantages of unrelated polarization, low crosstalk, high density of integration and low cost.