Abstract: In this paper the identifiability and identification algorithms for the non-minimum phase linear system with unmeasurable stationary input are discuxxed.The uncorrelation till n-th order called n-th order uncorrelation is defined,where n is greater than or equal to two.Its relation with commulants till n-th order is proven.This is the generalization of the relation between the traditional uncorrelation and covariance. Based on these definitions and the relations, the original constraint of the input of mutual independence and identical distribution is removed for the identifiability of the system. The entropy is introduced and the identifiability theorem is given when the entropy function is used to identify the system. Simulation is made and it verifies the correctness of theory and algorithms given in this paper.