The invention discloses a foot bath effervescent tablet and a preparation method thereof. The foot bath effervescent tablet is mainly prepared from 2% of a radix sophorae flavescentis extract, 2% of a fructus cnidii extract, 1% of a cortex phellodendri extract, 1% of a golden larch bark extract, 1% of a radix stemonae extract, 1% of a cortex dictamni extract, 18% of salicylic acid, 8% of benzoic acid, 15% of boric acid, 15% of sodium bicarbonate, 15% of tartaric acid, 20.5% of starch and 0.5% of magnesium stearate. According to the preparation method, the herbal extracts are adopted as main materials, so that a higher medicine effect is achieved, no irritation to the skin is caused, and multiple components with different effects and volatilization speeds are adopted for being compounded; the foot bath effervescent tablet has a main effect on diseases, such as foot itch, foot dryness, foot skin cracking, dermatophytosis, foot odours, foot sweat, rough cutin and foot fungus infection, of the foot skin surface, is used for bacterial inhibition and suitable for people with cold legs and cold feet, has no irritation to the skin, has an inhibition effect on foot fungus infection and also has the effects of promoting blood circulation to remove meridian obstruction, invigorating qi and blood, relieving fatigue, eliminating nervousness, improving sleep, nourishing the skin, balancing yin and yang, improving sub-health, adjusting the Zang-Fu function and the like.