The invention belongs to the technical field of genetic engineering and discloses the use of a key gene OsLSD2 associated with formation of rice aerenchyma. The rice key gene OsLSD2 controlling the formation of the rice aerenchyma can be used for increasing the height of plants and the nitrogen fertilizer utilization efficiency and/or yield of plants. The sequence registry number of the gene is AK111759. Through systemic study, the invention is the first to provide the biological functions of the key gene OsLSD2 controlling the formation of the rice aerenchyma. In the invention, an OsLSD2 overexpression material obtained by a transgenic means increases the expression of the OsLSD2 in laminae in roots greatly, so that the aerenchyma in the roots of rice plants change; and compared with a reference wide plant, the plants obtained by the transgenic material are taller and can better absorb and use nutrients, particularly nitrogen, and the nitrogen utilization efficiency and yield per plant are increased by over 30 percent.