The acrylic polymer latex was prepared successfully via semi-continuous seeded emulsion polymerization of methyl methacrylate(MMA), butyl acrylate(BA) and functional monomer butanedioicacid, 2-methylene-, 4-butylester (MBI) in water phase when mixed surfactants of tetradecyl dimethyl hydroxy propyl betaine and polyethylene glocolmono-nonylphenylether(OP-10) and 2,2'-azobis (2-methyl propion- amidine)dihydrochloride(V-50) were used to be emulsifier and initiator, respectively. The structure of the resultant latex is detected by Fourier transform infrared spectroscopy spectrum (ERR) and differential scanning calorimetry (DSC) also confirmed that latex is a kind of random copolymer. Factors, which have an effect on the emulsion polymerization and properties of the resultant latex, have been optimized. Results show that optimum conditions for preparing the latex is as follows: the amount of emulsifier, V-50 and MBI are 7%, 0.5% and 4%, respectively.