Transcranial photobiomodulation (tPBM) is a novel, non-invasive neurostimulation technique, which has shown compelling potential for cognitive improvement. Increasing neuroimaging studies have demonstrated that functional brain network models would sensitively and comprehensively delineate action mechanisms of multiple neurostimulation techniques. However, the action mechanism of tPBM based on functional brain network remain largely unknown. In this project, the investigators aim to investigate the effectiveness of tPBM on working memory for healthy older adults. Taking the randomized, single-blind controlled method, participants in the active tPBM group will take active tPBM, and those in the sham tPBM group will take sham tPBM. After that, the investigators will investigate the changes of working. Furthermore, based on the neuroimaging technique, the regulatory mechanism of tPBM in intervening older adults will be revealed from the perspective of altered brain functional networks. This study will provide evidence for understanding whether the tPBM has the potentially therapeutic effect on cognitive function for healthy older adults as a non-drug treatment, and further elucidating the potential brain mechanism, which are of great values in solving scientific and clinical practice issues.