Abstract: Coal fly ash is regarded as the important solid waste in the large coal power base,and above 600 million tons coal fly ash is generated annually.The utilization ratio is only 60%approximately,the most of fly ash is mainly stored in piles,which can cause serious environmental problems,and its resource utilization is of great significance.In this paper,the high alumina coal fly ash(HAFA)generated in Shanxi and the north of Inner Mongolia was adopted and researched.The basic physical property analysis shows that aluminum,silicon,iron,calcium are the main elements in the coal fly ash,which are in the form of mullite,amorphous silica and ferruginous spheres.Mullite is a stable phase.The reactivity of amorphous phase aluminum silicate is high,but its coordination structure is complex and the reactivity is different.Nowadays,in terms of its abundant aluminum/silicon resources,the main high-value research directions focus on the extraction of alumina and preparation of aluminum-siliconcomposite,in which the removal of amorphous silica is the key processing technology.In view of the occurrence morphology and quantitative analysis of amorphous silicon,firstly,the NMR analysis combined with EPMA was used to determine the complex structure of aluminium-silicate in amorphous phase.The silicon atoms mainly exist in five coordination structures:Q~4(4Al)/Q~4(3Al)/Q~4(2Al)/Q~4(0Al)/Q~2(1Al),and the content of Q~4(0Al)is occupied about 56.5%in the amorphous phase.Secondly,by means of acid-base combination method,the possibility of spontaneous reaction in alumina-silica zeolite was gradually weakened,active aluminium was selectively separated,and the active sites were exposed in large quantities,so as to realize the step-by-step separation of amorphous aluminium-silicate.Further,the efficient separation between mullite crystalline phase and aluminium-silicate amorphous phase was identified by ICP,XRF,XRD,SEM and EPMA.Two groups of parallel experiments were carried out,and the error of the test results was small.The results indicate that the content of silicon in amorphous phase is 57%-58%.The"bulging peak"of amorphous silica has disappeared,the grain structure of mullite enwrapped by the amorphous silica is exposed,which proves that amorphous silicon dioxide can be removed efficiently.There are three advantages of mild experimental conditions,minor errorand wide operating flexibility,which provides an important guiding significance for high value conversion and utilization of fly ash aluminium-silicon resources.