The present invention discloses one kind of light sound absorbing paint and its preparation process. The paint consists of acrylate emulsion of average grain size of 0.15-0.5 micron as the adhesive, open-pored expanded perlite as light aggregate, pigment, stuffing and assistants combined together. It is prepared through pre-mixing, dispersing grinding and blending via fast stirring. It has low density, non-toxicity, no smell, environment friendship, simple production, simple application, coating of 1-5 mm thickness, average sound absorbing coefficient higher than 0.4 and other advantages, and is suitable for use in household, meeting room, concert hall, theater, etc.