Abstract: We consider Gorenstein AC-projective modules over triangular matrix rings. Let T be a triangular matrix rings, where A and B are rings and U is a (B,A)-bimodule. We prove that if _BU is a flat module and U_A is a finitely generated projective module, then a le
ft T-module  is a Gorenstein AC-projective module if and only if M₁ is a Gorenstein AC-projective left A-module, φM is a monomorphism, and Coker φ^M is a Gorenstein AC-projective left B-module.

Key words:  , level module, Gorenstein AC-projective module, triangular matrix ring