Let T=(A 0 U B)be a formal triangular matrix ring,where A and B are rings and U is a(B,A)-bimodule.Let M=(M12M)φM be a left T-module.The results are proved that if T is a left GFPI-closed and left coherent ring,UA is flat,BU is finitely presented and pd(BU)<∞,then:(1)max{ G-FP-id(M1),G-FP-id(M2)}≤ G-FP-id(M);(2)G-FP-id(M)≤max { G-FP-id(M,),G-FP-id(M2)+1 };(3)max { lG-FP-id(A),lG-FP-id(B)}≤ lG-FP-id(T)≤max { lG-FP-id(A),lG-FP-id(B)+1 }.