Low-mass di-muons at CMS

The reconstruction of low-mass di-muon signatures at CMS with the data collected at 7.0 TeV c.m.s. energy, corresponding to 15 nb-1, will be presented in this talk. The work flow includes good run selection, selection of muons and quality cuts, determination of the momentum scale and resolution, and the determination of the trigger and detection efficiency and acceptance. The distributions for opposite sign and like-sign di-muons at the invariant mass range from 2 to 4 GeV are presented and compared with simulation.