The thermal properties and microstructural development of Zr65-xAl7.5Cu17.5Ni10Six, alloys during the annealing of amorphous alloys have been investigated by a combination of differential thermal analysis, differential scanning calorimetry, X-ray diffractometry and TEM. The glass transition temperature for the Zr65-xAl7.5Cu17.5Ni10Six alloys are measured around 6 65 K (392degreesC) with very lager deviation. However, the crystallization temperature increase with increasing the silicon c ontent to 10 at. % and obtains a relative lager temperature interval DeltaT(x) about 6 7 K. In addition, the value of T-rg the alloys with the addition of silicon present an increasing trend with increasing Si content. The activation energy of crystallization for the alloy 4Si was measured about 350 similar to 370 kJ/mol., as determined by the Kissinger or Avrami plot, respectively. These values are about 20 % higher than the activation energy of crystallization for the based alloy (310kJ/mol.). This implies that the silicon additions exhibit the effect of improving the thermal stability for the Zr-based amorphous alloy. The average value of the Avrami exponent n were calculated around 1.94 similar to2.45 for the alloys with silicon additions. This indicates that these six alloys present similar crystallization process, a diffusion controlled growth process with a decreasing nucleation rate.