Exploring the exotic quantum phenomena and the related ground state of the frustrated quantum magnets has emerged as a forefront area of condensed matter physics. These behaviors have been recognized to be related to the interplays of charge, spin, orbital, and lattice, which could lead to several intriguing phenomena. AReCh2 has a triangular lattice and no well-defined long-range magnetic order is observed in the single crystal form, which suggests the system as a potential candidate of quantum spin liquids. Therefore, further measurements are required to verify this conjecture. MuSR is sensitive to very small local magnetic field, and a powerful technique to investigate quantum spin liquid. In this proposal, we would like to use the MUSR (or EMU) spectrometer to measure the magnetic properties of NaYbS2 and NaYbSe2 single crystals.