A geogrid and a manufacturing method thereof. The geogrid comprises multiple ribs, and the multiple ribs are connected to each other at multiple junctions to form multiple cells. At each junction, two or more adjacent ribs of the multiple ribs are inserted into each other via inserts, and each junction is covered by a plastic material. The geogrid can easily be extended to a present state at a construction site, prevent tearing of apertures, prevent soil from leaking from the apertures, and prevent the inserts from rusting or corroding. Since the plastic material, the ribs, and the inserts are bonded to each other, separation strength at the junction is markedly increased. Preferably, an end portion of the insert is completely covered by the plastic material to form an end cap, and the plastic material and the ribs and the inserts are bonded to each other to form columns.