Abstract: The crystallization process and kinetics of ultralow -expansion lithium aluminosilcate glass ceramics were investigated using differential scanning calorimetric（DSC）,X-ray diffraction（XRD）, scanning electron microscopy（SEM） and other measuring technologies,and the effects of phosphate on the crystallization mechanism and structure of glass ceramics were analyzed.The results show that the introduction of phosphorous can influence the glass phase separation and phase transition process.On the one hand,phosphorus pentoxide can be as effective nucleation induction agent to result in phase separate, which is beneficial to the nucleation and crystal growth;on the other hand,it can increase the crystallization active energy（E）,make glass network structure rearrange difficultly,and restrain the grain growth.