Searches for low mass beyond the Standard Model (BSM) particles using the discovered Higgs boson at 125 GeV are presented in different possible channels, including invisible decays of the Higgs boson, the Higgs boson decays to new light bosons in which the light bosons decay to SM particles, and Lepton Flavour Violation (LFV) of the Higgs boson. The data is collected with the CMS detector at the LHC which corresponding to integrated luminosities of 19.7 and 2.3 fb$^{-1}$ at central-of-mass energies of 8 and 13 TeV, respectively. No excess of signal is observed. Upper limits are placed on the branching fractions of the Higgs boson decay to different BSM particles, assuming the SM cross sections. As well, the branching fractions of LFV Higgs boson are given. In addition, the combination of potential invisible decay modes of the Higgs boson is done for all channels and the results are interpreted in the context of Higgs-portal dark matter models.