A light combining structure including a first beam splitter, a first light source, a second light source and a second beam splitter is provided. The first light source is disposed on a first side of the first beam splitter to emit a first light and is provided with a first reflection surface. The second light source is disposed on a second side of the first beam splitter to emit a second light and is provided with a second reflection surface. The second beam splitter is disposed on a third side of the first beam splitter, wherein the first beam splitter allows the first light and the second light to partially reflect and partially penetrate, and the first reflection surface, the second reflection surface and the second beam splitter allow the first light and the second light to enter a fourth side of the first beam splitter after being reflected.