The effect of recrystallization fraction on quench sensitivity of Al-Zn-Mg-Cu alloys was investigated by means of thermal compression test, optical microscopy, and high-resolution transmission electron microscopy. Results show that the quench sensitivity, the size and area fraction of equilibrium phase for 7050 alloy increases with the increase of recrystallization fraction. The area fraction of recrystallization has a good linear correlation with the area fraction of equilibrium phase. When the recrystallization fraction increases from 10% to 58%, the relative hardness value increases from 7% to 17%, the length and thickness of the equilibrium phase increase from 265 nm and 35 nm to 422 nm and 82 nm, respectively, while the area fraction of the equilibrium phase also increases from 6.5% to 28.4%. The Al₃Zr particles in the sub-grained crystals have good coherency with the matrix, which are unfavorable to the equilibrium precipitation during the slow quenching process. However, the Al₃Zr particles in the recrystallized grains are beneficial to the equilibrium precipitation. The more recrystallization fractions, the more Al₃Zr particles that are incoherent with the matrix, so the more nucleation sites are precipitated by quenching, resulting in the increment of quench sensitivity.