To investigate the effect of different guidance methods on the cortical activation during fine motor imagery, a novel fine motor imagery method combining visual and auditory guidance is proposed. The goal is to explore the enhancement of cortical activation during fine motor imagery using different guidance approaches and to uncover the underlying patterns of cortical activity. An experimental paradigm was designed for fine motor imagery of the wrist, elbow, and shoulder joints, incorporating four guidance methods: simple visual guidance, auditory guidance, dynamic visual guidance, and dynamic visual combined with auditory guidance. ERD and ERS in the time and frequency domains were used as metrics to assess cortical activation. Energy distribution and brain network functional connectivity were utilized to observe the spatial distribution of cortical activity and analyze the degree of cortical activation under different guidance methods. The experimental results indicate that the dynamic visual combined with auditory guidance led to significantly higher ERD and ERS amplitudes compared to the other guidance methods. Additionally, under the visual and auditory combined guidance, the activated cortical regions were more extensive, and stronger synchronization and desynchronization were observed in multiple brain areas. Compared to simple visual guidance, auditory guidance, and single dynamic visual guidance, the dynamic visual combined with auditory guidance significantly enhanced cortical activation during fine motor imagery. This method provides a new guidance strategy for fine motor imagery training, contributing to improved training effectiveness and rehabilitation efficiency, with potential practical applications.