<p>For the low-strength shear wall where cross-sectional enlargement is constrained, the partial concrete replacement method at wall ends with conventional high-strength concrete offers a cost-effective strengthening solution. To evaluate the seismic performance of strengthened walls in comparison with both low-strength and design-strength reference specimens, cyclic lateral loading tests were conducted on 12 concrete walls with an aspect ratio of 2.4. Meanwhile, the effects of concrete replacement length on the seismic performance of the strengthened walls under different axial loads were analyzed. The results s indicate all specimens exhibited flexural failure and all strengthened specimens demonstrated excellent interfacial bond performance. The strengthened specimens exhibited significant enhancements in both load-bearing capacity (increased by 13 ~ 22%) and seismic performance compared to the low-strength specimens. Compared to the design-strength specimens, the strengthened specimens demonstrated a 2 ~ 12% increase in load-bearing capacity, while the improvement in seismic performance was found to be dependent on the replacement length under different axial loads. Additionally, the calculation model and formula of flexural capacity for strengthened specimens were proposed. The study demonstrates the strengthened wall can achieve seismic performance comparable to the design-strength wall, provided that the replacement length of the strengthened wall exceeds its calculated compression zone height at peak load. Beyond this critical length, increasing the replacement length further has negligible effects on seismic performance of the strengthened wall.</p>