The hydrotalcite was synthesized using brucite as the source of magnesium by the method of coprecipitation. The effect of synthesis parameters, such as Mg2+ concentration of solution, crystallizing time and temperature on their crystal structure were studied. The surface morphology was characterized by SEM, and the structure was characterized by XRD. Characterization of hydrotalcite showed that the particle size of the hydrotalcite with high degree of crystallinity was 10.0～0.1μm, and the Mg2+ concentration of solution, crystallizing time and temperature influenced the crystal structure. The proper Mg2+ concentration was 0.12M, and the optimal crystallizing time and temperature were 8h and 80°C, respectively.