Let G be a connected graph with vertex set V(G) and edge set E(G). The total Mostar index of a graph G is defined as: S t(G)=∑〖DD(X〗e=uv∈E(G)〖DD)〗〖JB(|〗t u(e)－t v(e)〖JB)|〗，where t u(e) denotes the number of vertices and edges closer to u than to v for an edge uv in G，and t v(e) denotes the number of vertices and edges closer to v than to u for an edge uv in G. To determine the extremal values and extremal graphs of the total Mostar index for bicyclic graphs of order n, based on whether the cycles share a common edge, bicyclic graphs are divided into two categories，and it proves that the total Mostar index of each category is greater than or equal to that of the extremal graphs. The extremal values of the total Mostar index for bicyclic graphs of order n are obtained. Thereby it extends the theoretical framework of the total Mostar index.