The invention discloses an eight-ingredient porridge and a preparation method thereof. The eight-ingredient porridge is composed of millet, rice, corn, barley, mung bean, red bean, peanut, soybean, red date, celery cabbage, sweet pepper and carrot. Every 100g of eight-ingredient porridge respectively contains 7-8g of millet, 7-8g of rice, 7-8g of corn, 7-8g of barley, 7-8g of mung bean, 7-8g of red bean, 7-8g of peanut, 7-8g of soybean, 10-12g of celery cabbage, 10-12g of sweet pepper and 10-12g of carrot. The preparation process comprises the following steps: selecting, soaking, boiling, drying, pulverizing and the like. The instant vegetable eight-ingredient porridge disclosed by the invention has the advantages of abundant nutrition, high vitamin content and good mouthfeel and flavor, is hygienic and convenient to carry and eat, and is a natural healthy food without any pigment or preservative. The production technique has the advantages of simplicity, low production cost, and obvious economic and social benefits.