In this paper the method proposed by Camentsev et al. (1977) is adopted to deduce the Al-occupancies in k-feldspar. 80 samples collected from different provinces of China have been studied and their T1(0), T1(m), T2(0) and T2(m)lculated. Meanwhile a T1(0) versus 2θ(-) -2θ(060)diagram and a T1(o) -To + T1(m) diagram are also plotted. The values of T, for all of these k-feldspars indicate they are micxocline with T1)>0.9 and monoclinic k-feldspars with T1﹤O.9. There is a gap between 0.5 and 0.7 for the Al-occupancies in T1 s shown in Fig 3. According to the experimental results, it is suggested that the ordering of Al/Si in natural k-feldspars are divided into two steps.The aluminium ions jump from T2(o) and T2(m) sitesinto T1(o)and T1(m) sites respectively, and then these in the T1(m) sites jump into the T1(o) sites. The first step is called the ordering in monoclinic structure and the second one the ordering in triclinic structure. The crystal will remain a monoclinic symmetry when the Al-occupancies in T1 are less than 0.9, but it will transform into a triclinic symmetry as soon as the Al-occupancies in T1 axe larger than 0.9.