The motivation of this article is to introduce a kind of orbit equivalence relations which can well describe structures and properties of Polish groups from the perspective of Borel reducibility. Given a Polish group G, let E(G) be the right coset equivalence relation G ω /c(G), where c(G) is the group of all convergent sequences in G.Let G be a Polish group.(1) G is a discrete countable group containing at least two elements iffThe notion of α-unbalanced Polish group for α < ω1 is introduced. Let G, H be Polish groups, 0For any Lie group G, denote G0 the connected component of the identity element 1G. Let G and H be two separable TSI Lie groups. If E(G) ≤B E(H), then there exists a continuous locally injection S : G0 → H0. Moreover, if G0, H0 are abelian, S is a group homomorphism. Particularly, for c0, e0, c1, e1 ∈ N, E(R c 0 × T e 0 ) ≤B E(R c 1 × T e 1 ) iff e0 ≤ e1 and c0 + e0 ≤ c1 + e1.