This paper is concerned with a linear-quadratic stochastic Stackelberg differential game, where players have asymmetric roles, with one leader and one follower in the context of two-person game. It is required that the information available to the follower is a sub-sigma-algebra of the one of the leader. By maximum principle and optimal filtering, a feedback Stackelberg equilibrium of the game is given. A special example is used to elaborate the result.