Amounts (A%，B%) and alternating stacking regularity (Re%)of two types of crystal layer (A-mica layer, B-smectite layer) in the structure of ten recto- rite samples from China were determined by direct Fourier transform method. It is known from the determination that A% varies in the range of 50.5%一 55.8%,B% 44.2%-49.5%,and Re% 72%一98.6%.The results show that tlxe two types of crystal layer (A and B) in the structure of natural rectorate do not strictly alternate in accord with the 1:1 regularity (A≠B, 1.0196%) and exhibit fairly perfect inteTStratified structure. With A% being 55.8%(> 55%)and Re% 72%(<90%)，the No.6 sample does not have perfect interstra- tified structure and thus seems to be a randomly interstratified rectorate/ mica mineral. In this paper, the formula Re% =A3B3 × 100/AB(%)is defined as regularity of rectorate. The pyercentage method has the advantages of easy cal- culation and high data reliability.