In this work, we study the average Steiner 3-eccentricity on block graphs with a fixed block order sequence. Two graph transformations are present on block graphs. Relying on the transformations, we establish both the lower bound and the upper bound for the average Steiner 3-eccentricity on block graphs with a fixed block order sequence. Finally, we devise an \(O(n^{2})\) algorithm to calculate the average Steiner 3-eccentricity on block graphes where n is the order of the graph.