The invention discloses eight-treasure porridge containing purple sweet potato and purple rice and a preparation method of the eight-treasure porridge. The eight-treasure porridge is prepared from the following components in parts by weight: 8-10 parts of diced purple sweet potato, 3-4 parts of purple rice, 10-12 parts of sticky rice, 3-4 parts of red rice, 6-7 parts of oat, 1.7-2.8 parts of diced Chinese chestnut, 4-4.5 parts of black rice, 2-3.6 parts of kidney beans, 0.5-1.3 parts of expanded black rice meal, 16-20 parts of white granulated sugar, 1.3-3.9 parts of coconut pulp, 0.15-0.3 part of sucrose ester, 0.02-0.04 part of ethylene diamine tetraacetic acid, 0.06-0.16 part of sodium tripolyphosphate, 0.05-0.11 part of sodium hexametaphosphate, 0.03-0.09 part of edible salt and 226-231 parts of water. The eight-treasure porridge disclosed by the invention is eggplant, strong in aroma, and appropriate in taste viscosity and softness, and various raw materials are blended with one another in flavor, so that the eight-treasure porridge is perfect in color, aroma and taste, healthy and nutrient.