In order to increase the performance and to produce environment friendly aero engine, it is necessary to reduce the weight of the engine. A significant proportion of an engine's weight is due to the large castings used to form the main non-rotating structures. Replacement of these large castings with circular structures fabricated by assembling uniformly segmented circular components could provide a significant weight reduction. Due to various advantages of fabricated rigid structure of an aero engine casing, this article proposes that components should be assembled while considering optimum mating sequence to minimize assembly error and to reduce assembly time and cost. The algorithm based on connective assembly model is proposed to predict stage-by-stage assembly variations. A computer program is also developed to perform automated tolerance analysis and to find optimum mating sequence of component. The assembly variations are minimized based on three criteria of selection of assembly mating sequence. The results have shown that the three criteria may be used every time for tolerance analysis and to minimize variation propagations in the assembly of rigid circular structures.