An ultraviolet detection system comprises a global positioning device for receiving signals transmitted from global positioning satellites, and generating global positioning satellite distribution data and current position data; and a processor, coupled to the global positioning device, for generating ultraviolet intensity information according to the current position data and the global positioning satellite distribution data. The processor generates ultraviolet intensity information more accurately according to a current time data, which is transmitted from the global positioning satellite or is automatically generated from the global positioning device.