Improved drainage device

An improved drainage device comprises at least one layer of water collecting plate and a water collecting assembly formed by geotextiles wrapped on the outer surface of the at least one layer of water collecting plate. The improved drainage device is characterized in that each water collecting plate comprises a connecting plate and pits which are distributed on the connecting plate and recessed towards one side of the connecting plate. Drainage intervals are reserved between the adjacent pits. The improved drainage device has the advantages that drainage channels which extend in all directions are formed by utilizing the drainage intervals reserved between the pits arranged on the water collecting plate, thereby satisfying the requirements for water collection and drainage. The improved drainage device further has the advantages of being difficult to block, simple in structure, low in cost and convenient to install. The water collecting plate can serve as a water collecting component, can also serve as a drainage pipe by increasing the thickness (multilayer combination), and can be connected with drainage pipes of other types to form the combined drainage device, thereby being multiple in functions.