On May 22, 2021, a magnitude 7.4 earthquake struck Maduo County, Qinghai Province, China. As there is only one permanent seismic station in the focal region of the Maduo MS7.4 earthquake, the resolution of the previous deep structure analysis is low. In order to further study the deep seismogenic environment of the Maduo MS7.4 earthquake and monitor the aftershock activity, we deployed a dense array of 150 short-period seismic stations for a one-month observation period. Utilizing the data from the dense array, we conducted research on earthquake location, three-dimensional high-resolution seismic imaging, focal mechanism solutions, and shear wave splitting. The results show that the aftershocks are mainly distributed along the surface rupture, with obvious velocity heterogeneities around the main rupture. The delay times in the intensive area of aftershocks along the main rupture are significantly greater than those on the north and south sides outside the intense aftershock zone. The distribution of aftershock sequences, fast wave polarization, and surface rupture alignment around the main rupture zone exhibit strong consistency and segmentation characteristics. However, they only align with the strike of the middle segment of the seismogenic fault (Jiangcuo fault), displaying a NWW direction, rather than with the western and eastern segments. Near the inflection points of the three segments, focal mechanism solutions reveal two thrust earthquakes, while three-dimensional seismic imaging identifies two regions of high- and low-velocity transitions. The aftershocks are mainly distributed on the north side of the main rupture, with larger delay times observed on the north side compared to the south side. On the north side of the main rupture, there is a high-velocity anomaly dipping northwards, while the south side generally showing low-velocity. The shape of seismogenic fault, as revealed by a high-resolution catalog, also indicates a northward dip. The eastern segment of the main rupture is not only the region with the most intensive distribution of aftershocks and the mainshock, but also the region with the largest scale of high-velocity anomaly and the larger delay times in the focal region. These characteristics suggest that the stress accumulation during the seismogenic process of the Maduo MS7.4 earthquake is mainly concentrated in the aftershock-intensive area along the north side of the main rupture, with the eastern segment, including the main earthquake, being the strongest area of stress accumulation and seismic activity due to being blocked by the high-speed anomaly in the east.