In order to solve the difficulties of traditional models in measuring the constellation effectiveness with continuous time and limited states, a BDP-ADC(birth-death process-availability, dependability, capability) model for evaluating the effectiveness of Iridium is constructed. Firstly, the birth and death process is used to describe the transition process of constellation state, and the limit distribution of the state transition process is obtained, and the availability of Iridium is defined. Then, Kolmogorov forward equation is used to measure the dependability of the constellation in the mission execution process. Then, according to the established Iridium capability evaluation index system, the weight of indexes is obtained by using the entropy weight method, and the constellation capability is calculated with the full probability formula. Finally, the dynamic relationship of Iridium constellation effectiveness is obtained by using the BDP-ADC effectiveness evaluation model, and the Iridium constellation effectiveness is obtained, which provides a basis for constellation design and optimization.