Abstract <p>The semiquantitative correlation between precipitates and tensile twin in Mg–5Sn alloy is investigated using three different quasi-in situ alternant compression and aging processes (1—A₃₀ T_{2 pct} T_{2 pct} T_{2 pct}, 2—T_{2 pct}A₅ T_{2 pct}A₅T_{2 pct}, and 3—T_{2 pct}A₁₅T_{2 pct}A₁₅T_{2 pct}). The results indicate that precipitation characteristics vary with the sequence of compression and aging, and respectively influence on the nucleation and expansion of twins. Prior aging before compression in Process 1 increases precipitation density to 15.1 N_A/<i>μ</i>m⁻² and reduces the area fraction of twin to 6.8 pct at an initial 2 pct strain, compared to Processes 2 and 3 with direct compression (twin area fraction of 19.8 and 22.9 pct, respectively). As aging and compression strain proceed, precipitates form at twin boundaries or within twin during the alternant compression and aging in Processes 2 and 3, effectively hindering the twin expansion. This effect becomes more pronounced with increased precipitation density. Strain. In Process 3, which features high precipitation density within twin region (22.4 N_A/<i>μ</i>m⁻²), the twin area fraction increases slightly by 6.2 and 16.7 pct at 4 and 6 pct compression strain. Ultimately, it exhibits a lower final area fraction of 29.1 pct compared to that of process 1 (43.8 pct). The present study provides valuable guidance for microstructures design based on the interaction of precipitation and twins.</p> Graphical Abstract <p></p>