The invention discloses an acid-resistant pseudomonas koreensis strain CLP-7 which is capable of preventing diseases and promoting growth, and can be used for biocontrol. The acid-resistant pseudomonas koreensis strain CLP-7 is preserved at China General Microbiological Culture Collection Center, on 27th, October, 2016, and the preservation number is CGMCC No.13204. The antibacterial spectrum of the acid-resistant pseudomonas koreensis strain CLP-7 is relatively large; the acid-resistant pseudomonas koreensis strain CLP-7 is capable of inhibiting growth of Phytophthora parasitica var. nicotianae, Ralstonia solanacearum, and Alternaria alternata Keissler; the antagonistic activity under acidic conditions is high, the acid-resistant pseudomonas koreensis strain CLP-7 is capable of producing siderophore, possesses protease and glucanase activity, and potassium releasing capacity. The results of biocontrol pot experiment show that the acid-resistant pseudomonas koreensis strain CLP-7 is capable of preventing under acidic soil conditions, and promoting growth and chlorophyll synthesis of tobacco seedlings in acidic soil, so that the acid-resistant pseudomonas koreensis strain CLP-7 and microorganism bacterium agents of the acid-resistant pseudomonas koreensis strain CLP-7 can be used for preventing tobacco fungi and bacterial root and stem diseases under continuous cropping or acidic soil conditions effectively, and is high in application value.