In underground mining activities with medium-long hole blasting, fan-shaped hole blasting is one of the important methods adopted for medlium-thick orebody recovery due to its advantages of reduced development workload, simple structure, high recovery efficiency, and low cost. However, most fan-shaped hole blasting neglects sidewall control in stopes, leading to extremely uneven sidewalls after fan-shaped blasting in complex stope environments, which significantly impacts the safety and economic benefits. In the engineering background of a copper mine, this study integrates theoretical analysis and field tests to address the issue of stope sidewall blasting control. By modifying the stope structure and hole layout under the original mining method, a dual-controlled sidewall fan-shaped medium-long hole strip open-stope mining method with subsequent backfilling is proposed. This approach effectively optimizes explosive energy distribution along the stope sidewalls and within the stope and incorporates smooth blasting principles. Calculations determined a hole spacing of 0.8 m corresponding to a charge diameter of 36 mm. A hole-by-hole initiation network with outside-hole delays was designed, and key techniques were explained, enabling single-blast initiation of up to 7 rows while maintaining production efficiency. Industrial trials in Stope 1000-1-4 demonstrated smooth post-mining sidewalls, validating the method's effectiveness.