The invention provides primer styrene-acrylic emulsion resistant to fresh cement efflorescence. The primer styrene-acrylic emulsion resistant to fresh cement efflorescence comprises components of water, styrene, methyl methacrylate, iso-octyl acrylate, butyl acrylate, acrylic acid, methacrylic acid, methacrylamide, an anionic emulsifier, cross-linking monomers, special functional monomers, an initiator, an oxidizing agent and a reducing agent, and is prepared from the components in parts by mass as follows: 80-130 parts of water, 30-60 parts of styrene, 20-80 parts of methyl methacrylate, 10-20 parts of iso-octyl acrylate, 20-80 parts of butyl acrylate, 0.5-5 parts of acrylic acid, 0.5-5 parts of methacrylic acid, 1-5 parts of methacrylamide, 5-20 parts of the anionic emulsifier, 1-5 parts of the cross-linking monomers, 0.5-2 parts of the special functional monomers, 0.2-1 part of the initiator, 0.1-0.5 parts of the oxidizing agent and 0.1-0.5 parts of the reducing agent.