The invention discloses an AlGaN-based bicolor solar blind ultraviolet detector and a manufacturing method thereof. The detector comprises a substrate, a buffer layer, a n-i-p-i-n unit, an upper table top, a lower table top, an n type ohmic contact metal layer, a p type ohmic contact metal layer, a thickened metal layer and a silicon dioxide layer, wherein the n-i-p-i-n unit comprises a lower n type doping layer, a lower i type active layer, a p type doping layer, an upper i type active layer and an upper n type doping layer which are sequentially grown on the buffer layer; the upper table top is formed by etching the upper n type doping layer, the upper i type active layer and two sides of the p type doping layer; the lower table top is formed by etching the p type doping layers on two sides of the lower portion of the upper table top; and the n type ohmic contact metal layer is grown on the surface of the upper n type doping layer and the upper surface of the lower n type doping layer on one side of the lower table top. The p type ohmic contact metal layer is grown on the upper surface of the p type doping layer on one side of the upper table top; the thickened metal layer is grown on the n type ohmic contact metal layer and the upper surface of the p type ohmic contact metal layer, and the size of the thickened metal layer is larger than that of the ohmic contact metal layer below the thickened metal layer.