This paper presents the integration design and Implementation of a longitudinal automation system with the interaction of human-in-the-loop (HITL), The proposed system has a hierarchical structure composed and consists of an adaptive sensory processor, a supervisory control and a regulation control. The adaptive sensory processor routes the information from on-board sensors to avoid missing detection of the vehicle ahead. Based on the recognized measurement from the adaptive sensory processor, the supervisory control determines the desired velocity for the vehicle so as to maintain safety and smooth operation in different modes. The regulation control utilizes soft-computing technique and drives the throttle action to execute the desired velocity commanded from the supervisory control. The feasible sensory distance is within 40 m, and the according driving velocity can achieve 100 km/h upward. The challenge in low velocity operation can also be handled by the regulation control against gear changes and torque converter. Among experimental tests under various kinds of traffic flows, the system validness is exhibited and also the preferable comfort is achieved through the examination of International standard ISO 2631.