A device and method for determining the assay result is disclosed. The device includes a photoelectric detection circuit and a processor, and an optical detection device which is set with a detection zone and a blank zone for measuring assay results, and the photoelectric detection circuit detects the light-reflection intensity signal, and feeds back the detected information to the processor, and the processor is preset with a threshold value changing with time, and determined value processed by the processor is compared with the preset threshold value to obtain the result of assay. The method for determining the assay result display the result when confirmed determined value is bigger than the preset threshold value or can not reach preset threshold value within a fixed time or detected signal can not be determined, wherein the threshold value changes with the time. The device and method for determining the assay result work more efficiently, measure more accurately and cost less than the prior art.
