The invention provides a Ln-MOFs nanosphere and a preparation method and application thereof. The preparation method includes the steps that the soluble salt and ligands of a lanthanum (Ln) system aredissolved in a solvent, a capping agent is added until the pH is not changed, then an additive is added into the system, the temperature rises for a reaction, treatment is performed after the reaction, and the Ln-MOFs nanosphere is prepared. Through the provided method, the Ln-MOFs nanosphere high in controllability, yield and homogeneity can be prepared, and the Ln-MOFs nanosphere serves as an anode material after being compounded with mesoporous carbon, can be prepared into oxygen positive electrodes applied to lithium-air batteries, can improve the specific capacity of a mesoporous carboncell, and improves the rate performance and the cycle performance; the problems are solved that large-size Ln-MOFs are poor in conductivity and structural stability in the cycling process and the collapse of a frame structure can be easily caused. The preparation method is simple and easy to achieve, and has high practicability and economic value.