The invention discloses a focusing module and an assembly process thereof. The focusing module comprises a lens base component, a lens cone component, an image sensor component and a fine-tuning component, wherein an image sensor in the image sensor component is clung to the upper surface of a circuit board, the lens cone component is fixed on the lens base component, the fine-tuning component is located between the lens base component and the lens cone component, the lens base component is mounted on the image sensor component, and the lens cone component comprises a lens cone internally provided with a first lens. According to the invention, the lens base is directly mounted on the image sensor, requirements on the flatness and centrality of the circuit board are lowered, and meanwhile, owing to the added fine-tuning component, the focusing is convenient, the assembly time is saved, the production capacity is effectively improved, and mass production is facilitated.