In order to facilitate an analysis for the maintenance planning, most dynamic grouping models assume that the repair time is negligible. This assumption may be unrealistic and limits the application of these models in many real situations. The main objective of this paper is to develop a dynamic grouping strategy for complex structure systems with taking into account the durations of repair actions. Analytical method is used instead of simulation for the evaluation of total maintenance cost. This analytical method helps to overcome the computational time problem, which often is a big problem for the maintenance optimization of systems with a large number of components. A numerical example is presented to show how the proposed grouping approach can be used for the maintenance planning of a complex structure system containing 12 components.