The invention discloses a broad-spectrum-disease-resistance growth-promoting stress-tolerant Pseudomonas azotoformans strain and application thereof. The broad-spectrum-disease-resistance growth-promoting stress-tolerant Pseudomonas azotoformans is Pseudomonas azotoformans WXCDD51 of which the collection date is July 12th, 2016, and the collection number is CGMCC No.12760. The biocontrol strain has the characteristics of ultraviolet resistance and drought resistance, has higher preventing and treating effects on gray mold and leaf mold of tomato, can inhibit fusarium wilt of multiple crops, basal stem rot of corn, seedling blight of rice, root rot of acanthopanax, corynespora leaf spot of cucumber, anthracnose of cucumber, leaf blight of corn, leaf spot of tomato, Sclerotinia sclerotiorum of sunflower, Botrytis cinerea of strawberries, Fusarium oxysporum, Verticillium Fusarium, Alternaria alternata and other fungus diseases, has a growth-promoting action on tomato seeds, and is capable of improving the fruit quality and lowering the rotting rate.