Abstract: One problem of the Reconstruction Conjecture isfind a complete set of invariants of a graph. The spectral moments sequence is an important invariant of a graph， which connected closely to the numbers of closed walks. On analysing the structure feature of trees， first find all tree subgraphs which can generate closed walks of length eigth， then provid 8th spectral moment calculation formula.

Key words: adjacent matrix, [kth]spectral moment, tree, star tree