A use of triterpenes for improving algal bloom is disclosed, wherein the triterpenes is administered to a freshwater waterbody to inhibit over proliferation of algal cells in the freshwater waterbody. The triterpenes is selected from dehydroeburicoic acid, dehydrosulfurenic acid or 4,7-dimethoxy-5-methyl-1,3-benzodioxole.一種三萜類化合物用以改善藻華現象之用途,該三萜類化合物係投於一淡水水體,以抑制該淡水水體中藻細胞之過度增殖;其中,該三萜類化合物係選自去氫齒孔酸、去氫硫色多孔菌酸或1,4-二甲基-2,3-亞甲二氧基-5-乙苯。