The invention discloses an emulsion-type fluid loss reducer for oil well cement. The emulsion-type fluid loss reducer comprises, by weight, 50-60% of styrene-butadiene latex, 10-15% of redispersible emulsion powder, 1-3% of suspension stabilizer and the balance water. The emulsion-type fluid loss reducer for the oil well cement has the advantages that containing the styrene-butadiene latex, the fluid loss reducer for the cement is capable of forming a netted structure when being added into the cement, and the netted structure is formed through aggregation of the styrene-butadiene latex and is interwoven with a cement hydrate remarkably, so that set cement is endowed with a certain tenacity to be prevented from brittle rupture, shaft sealing integrity is improved, and shaft recovery rate is increased; the suspension stabilizer is capable of preventing the styrene-butadiene latex from flocculating in cement paste.