Acrylate polymer latices with soft core and hard shell were synthesized via the emulsion polymerization of β-hydroxy propylmethacrylate （HPMA） and methacrylic acid （ MAA）, and the corresponding re-dispersible powder was also prepared. Moreover, the influence of HPMA dosage on the film-forming ability, the re-dispersibility and the water resistance of the original latex and its re-dispersible powder were discussed. Experimental results show that, at a HPMA dosage of 1.2% （mass fraction, the same below） , the film-forming ability and the water resist- ance behavior of the original latex and its re-dispersible powder are optimal and the re-dispersibility is well maintained. The absorbance analysis indicates that, when the HPMA dosage is not more than 1.2%, the powder possesses excellent re-dispersibility, high dispersity （ up to 90% ） and small mean absorbance variation （ less than 10% ）. DSC results show that the film of the original latex is of two glass transition temperatures; one is 6. 98℃ and the other is 30. 11 ℃, which means that the polymer particles have a two-phase core-shell configuration. This configuration is also verified by TEM photographs. Moreover, SEM results demonstrate that both the original latex and the re-dispersible powder are of excellent film-forming ability, and that micro-phase separation occurs during the film-forming of the original latex, which further testifies the core-shell configuration of the latex.