The utility model provides a beta structure of tent sunshading board sets up at the rectangle frame both sides tip of compriseing violently pipe and standpipe, folding mechanism includes the bracing piece, and the bracing piece includes that vertical rod reaches and vertical rod vertically head rod and second connecting rod, and the head rod setting is in vertical rod's end, and the second connecting rod sets up at vertical rod's middle part, and the head rod passes through the articulated mode and fixes the outside at the rectangle frame, the middle part of standpipe is provided with the third connecting rod that stretches out downwards, is provided with the primary and secondary pole of slope between second connecting rod and the third connecting rod, and the both ends of primary and secondary pole are articulated mutually with second connecting rod and third connecting rod respectively, and the cover is equipped with slidable plastics fastener on the primary and secondary pole. Through this folding mechanism, the tent sunshading board can set up with the tent is integrative to can open fast and pack up.