An optical volume measurement device includes a main body, a pair of photographic lenses, an optical distance measuring unit and an optical projecting unit. The photographic lenses are disposed on the main body. Each of the photographic lenses has an image acquiring area extended forwardly therefrom and captures images within the image acquiring area separately, and a resolution distance range is formed in front of each photographic lens. Each photographic lens identifies the image within the resolution distance range, and image acquiring areas are overlapped to form a measurement area within the resolution distance range. The optical projecting unit is disposed on the main body and forwardly project an optical alignment indicator in a projection area. The projection area is located in the measurement area within the resolution distance range.