The purpose of this research is to propose the method providing the visually impaired users with environment understanding via modality conversion from visual distance to haptic vibration information. According to studies on ecological perception, optical flow, which represents dynamical visual variation, plays significant roles in environment understanding for human. We have developed a head-mounted wearable device equipped with a 2-dimensional distance sensor and five vibro-motors arranged around the head. The vibration magnitude of vibro-motors is defined as not static distance to the obstacle but dynamic distance variation caused from the user movement. The vibro-stimuli are generated based on the optical flow characteristics. Thus, if the user moves to the obstacle dynamically, the user feels stronger vibration; in contrast, if the user pauses, the user feels no vibration since the distance to obstacles keeps constant. To evaluate basic performance of the proposed method, we asked five blindfolded subjects to walk toward the wall 50 times each. First 10 trials performed by each subject are considered as practice phase; hence, the remaining 40 trials are evaluated. In total 200 trials, the 97.5% of trials are considered as success ones; the almost subjects were able to perceive the wall existence and stopped without the collision with the wall. The experiment demonstrated the basic validity of our proposed method. The main contribution of this paper is utilizing dynamic distance variation to determine vibration magnitude and providing the user with vibro-stimuli simulated by optical flow to support the user’s localization in the environment.