The invention relates to a preparation method of a heatstroke relieving agent used in outdoor power operations. The following raw materials are used in the method: 35 parts of salvia miltiorrhiza, 35 parts of asiatic cornelian cherry fruit, 35 parts of lotus leaves, 30 parts of spina date seed, 30 parts of dark plum, 25 parts of heartleaf houttuynia herb, 25 parts of prepared rehmannia root, 22 parts of dwarf lilyturf tuber, 22 parts of osmanthus fragrans, 22 parts of white paeony root, 22 parts of eupatorium fortunei, 22 parts of dandelion, 20 parts of Indian bread, 20 parts of dried tangerine peel, 20 parts of polygala tenuifolia, 20 parts of acorus calamus, 18 parts of trichosanthes kirilowii Maxim, 18 parts of mulberries, 18 parts of campsis grandiflora, 18 parts of palmleaf raspberry fruit, 15 parts of fragrant solomonseal rhizome, 15 parts of Chinese magnoliavine fruit, 15 parts of common anemarrhena rhizome, 10 parts of morinda root, 8 parts of plantain herb and 8 parts of liquorice. The preparation method has the beneficial effects that the medicines are jointly used and complement each other; the heatstroke relieving agent has obvious and stable heatstroke treatment effects and broad application prospects.