We develop a new tool, the time inhomogeneous Poisson equation in the whole space and with a terminal condition at infinity, to study the asymptotic behavior of the non-autonomous multi-scale stochastic system with irregular coefficients, where both the fast and the slow equation depend on the highly oscillating time component. In particular, periodic, quasi-periodic and almost periodic coefficients are allowed. The strong convergence of double averaging principle as well as the functional central limit theorem with homogenized-averaged diffusion coefficient are established. Moreover, we also obtain rates of convergence, which do not depend on the regularities of the coefficients with respect to the time component and the fast variable.