Studies of longitudinal de-correlation of anisotropic flow provide unique constraints on the initial conditions and dynamical evolution of the quark-gluon-plasma in heavy-ion collisions. With data collected by the STAR experiment at RHIC, the factorization ratio for flow harmonics, $r_n(\eta^a, \eta^b) (n = 2, 3)$, are obtained over a wide $\eta$ range for 27 and 54.4 GeV Au+Au collisions as a function of centrality and transverse momentum. Comparing to results from LHC and 200 GeV Au+Au collisions, we observe a clear collision-energy dependence indicating a stronger longitudinal de-correlation at lower collision energies. The results provide new insights into the three-dimensional modeling of the evolution of relativistic heavy-ion collisions and the shear viscosity of the QGP, especially their collision energy dependence. Comparison with the hydrodynamic model calculations will be included.