Meridian Project, a detailed investigation of the characteristics of field-aligned irregularities in the F region of the ionosphere in low latitude areas in China was conducted. During this process, a rare V-shaped structure of irregularities was identified. Further mapping of the fan-shaped diagram and analysis of its time-frequency characteristics in conjunction with ionosonde data were performed. The analysis results were compared with the airglow images of the corresponding period, and the results show that this V-shaped structure of irregularities is caused by the modulation of the background electric field of the ionosphere by gravity waves, leading to changes in its dynamic state.