Spin wave is considered an alternative carrier with great promise for information sensing. The feasible excitation and low-power manipulation of spin waves still remain a challenge. In this regard, natural light enables spin wave tunability is profoundly investigated in Co60 Al40 alloyed film. A reversible manner with 2° of the critical angle of the body spin wave is achieved successfully. Meanwhile, an eye-catching shift (817Oe) of the ferromagnetic resonance (FMR) field is obtained optically, leading to changes in magnetic anisotropy. Based on the modified Puszkarski's surface inhomogeneity model, the sunlight control of spin-wave resonance (SWR) can be comprehended by a photoelectron-doping-induced effective surface magnetic anisotropy change. Furthermore, the body spin wave is modulated stably with natural light illumination, confirming a non-volatile, reversible switching behavior. This work has both practical and theoretical importance for developing future sunlight-tunable magnonics/spintronics devices. This article is protected by copyright. All rights reserved.