The present invention provides a light coupler and a manufacturing method thereof. The light coupler of the invention includes a plurality of light input terminals, a plurality of light output terminals, a plurality of half mirrors, and an optical wave guide connecting the plurality of the light input terminals, the plurality of the light output terminals and the plurality of the half mirrors. The optical wave guide has kinked line shape and each of the plurality of half mirrors is placed at a respective corner of the kinked line shape. Especially, the kinked line shape includes a polygon network.