We study the potential of the future Higgs factories, including the ILC, CEPC, and FCC-ee with \sqrt{s} = 240-250 GeV on discovering axion-like particles (ALPs) through various production channels e^+ e^- --> f fbar a, where f = e, \mu, \nu, followed by the diphoton decay of the ALP. We find that g_{a\gamma\gamma} can be down to around 1.5 × 10^−4 GeV^−1 for M_a = 0.1 − 6 GeV, which is currently not ruled out by any other experiments.
In the second part of the talk, I discuss a scenario of muonphilic ALP produced via pion decays in the atmospheric air shower, \pi^+ -> \mu^+ \nu a, followed by diphotpn decay of the ALP. After propagating tens of kilometers, the ALPs decay into photon pairs, which can be detected inside large-volume Cherenkov detectors near the Earth surface, such as Super-K. We find the present SK observation can constrain on muonphilic ALP in certain mass range.