The invention discloses a multifunctional aquatic weeds harvester, which mainly comprises a ship body, wherein a grabbing cutter for cutting aquatic weeds, a reticular conveyor belt for conveying theharvested aquatic weeds, a spiral extruding conveying device for extruding water from aquatic weeds, and a storehouse for collecting weeds after squeezing are arranged successively on the ship body. The front and back ends of the ship body are respectively connected with the reticular conveyor belt and the storehouse. The spiral extrusion conveying device is arranged above the middle part of the ship body. A grabbing cutter comprises a reciprocating cutter and a drum-type cutter which are arranged at the front of the reticular conveyor belt. Aquatic weeds are collected and stored by the storehouse through the grabbing cutter, the reticular conveyor belt and the spiral extrusion conveying device in sequence during harvesting operation. The storehouse and the ship body are separable. According to the multifunctional aquatic weeds harvester, the processes of cutting and squeezing of the aquatic weeds can be simultaneously achieved. The aquatic weeds are arranged in the detachable storehouse after being dewatered; so that further transportation and utilization are facilitated and one-stop treatment is achieved. The grabbing cutter can simultaneously harvest the aquatic weeds on the water surface and underwater and the aquatic weeds can be harvested in a wide range.