A large variety of exotic magnetic structure and relevant magnetic properties is observed in honeycomb layered oxides. Recently Koo et al. showed two magnetic contributions i.e. quasi-free spins at low-temperature and a spin-gapped magnetic subsystem in Li3Cu2SbO6. Static magnetic susceptibility and ESR data suggest ferromagnetic-antiferromagnetic alternating chains with JFM = -285 K and JAFM = 160 K with a significant amount of Li-defects in the chain. There are about 0.8 quasi-free spins S = ½ per formula unit which cannot be explained by Cu2+ ions residing on Li position. Susceptibility data fails to determinant the small difference between AFM-AFM alternating chains and AFM-FM ones with dominant ferromagnetic coupling. It is crucial to investigate low temperature magnetic structure using neutron diffraction measurement using WISH spectrometer in Li3Cu2SbO6.