The invention relates to prestressed grid anchorage technology for side slope governance, in particular to a prestressed grid anchorage structure for side slope governance and a construction method thereof. Pressure dispersion type anchor ropes are adopted, and each two anchor ropes are butted and tensioned with steel stranded wires from vertical, horizontal and opposite anchor holes in a middle part so as to save outer anchor pier and tension repeatedly. The non-bonded steel stranded wires are longitudinally and transversely crossed and arranged to form a grid, and a node is an anchorage end or a tensioning end. The composite side slope anchorage structure is simple and convenient to construct, overcomes the defects that the prior reinforced concrete framework beam anchorage structure is easy to crack and deform, is difficult to construct and the like, and makes full use of the strength of the high-strength and low-looseness non-bonded steel stranded wires to combine the light and flexible tensioned grid and the pressure dispersion type anchor ropes into a whole so as to obtain more effective and safer anchorage effect. Moreover, the side slope governance and green ecological protective measures are combined.