The invention discloses a navigation-mark cluster system and a cluster monitoring method for monitoring marine pollutant by using the navigation-mark cluster system. According to the navigation-mark cluster system, parking aprons for parking unmanned aerial vehicles are arranged on a navigation mark light frame, charging devices for charging the unmanned aerial vehicles are arranged on the parking aprons, solar panels are connected with a power module, the power module comprises a storage battery and an energy charging and supply circuit, charging receiving circuits are arranged on the unmanned aerial vehicles, and a wireless communication device and an image processor are arranged on the navigation-mark light frame. The cluster monitoring method for monitoring the marine pollutant includes the steps that each unmanned aerial vehicle departs when receiving a departure order, a camera device transmits image signals to the image processor on the navigation-mark light frame, and the image processor sends the processed image signals to a shore-based control center. The cluster monitoring method for monitoring the marine pollutant can monitor a wide range of sea areas per unit time, therefore energy consumed by the unmanned aerial vehicles flying from a land charging base to an operating water area is saved, meanwhile, the navigation-mark cluster system is high in adaptability, reliability and safety, supports unmanned management, and exactly meets the practical needs for marine operation of the unmanned aerial vehicles.