Disclosed are an optical assembly and a manufacturing method thereof, and a polarizer. The optical assembly includes: a first film layer; a second film layer disposed opposite to the first film layer; and multiple light absorption patterns disposed on the first film layer. The first film layer and the second film layer are light transmissive film layers, holes are disposed in the second film layer at locations corresponding to the light absorption patterns, and a dimension of an end of each hole away from the light absorption pattern is smaller than a dimension of an end of the hole close to the light absorption pattern. The optical assembly further includes light transmissive protrusions protruding into the holes.