The invention discloses a metalaxyl-M and propamocarb hydrochloride compounded aqueous solution and an application thereof. The metalaxyl-M and propamocarb hydrochloride compounded aqueous solution is prepared from, by weight, 1-20% of metalaxyl-M, 1-60% of propamocarb hydrochloride, 3-30% of thymol, 5-20% of a surface active agent, 0.1-2% of stabilizer, 0.1-0.3% of defoamer and the balance of water. The metalaxyl-M and propamocarb hydrochloride compounded aqueous solution is efficient, safe and environment friendly, synergistic effect on the component is achieved, crop output can be increased, quality of fruit is improved, cost is lowered and generation of drug resistance to bacteria is beneficially suspended; the metalaxyl-M and propamocarb hydrochloride compounded aqueous solution can be used for preventing and controlling crop diseases of citrus burning disease, corynespora cassiicola, pepper phytophthora blight, rice seedling blight and rice blast, plasmopara viticola and the like.