Vertical take-off and landing unmanned aerial vehicles (VTOL UAVs) are expected to perform dangerous mission such as rescue and exploring disaster site alone. As for the operation of a UAV in a rescue mission, teleoperation is preferred. This paper describes teleoperation of a miniature tail-sitter VTOL UAV. A teleoperation system is developed to navigate a tail-sitter UAV. A velocity estimation method for outdoor flight is described and a velocity control strategy based on attitude control for indoor hovering of tail-sitter VTOL UAVs is proposed. In order to verify the teleoperation system and velocity control strategy, indoor exploration and target tracking teleoperation are performed in this paper. Through the experiments, the operator successfully controlled a teleoperated tail-sitter VTOL UAV with non-line-of-sight. In addition, a preliminary obstacle avoidance system is also implemented to assist operator.