In this paper, it is proved that a trans-Sasakian 3-manifold is locally symmetric if and only if it is locally isometric to the sphere space S 3 (c 2), the hyperbolic space H 3 (−c 2), the Euclidean space R 3 , the product space R × S 2 (c 2) or R × H 2 (−c 2), where c is a nonzero constant. Some examples are constructed to illustrate main results. We also give some new conditions for a compact trans-Sasakian 3-manifold to be proper.