Abstract: Objectives: Accurate and reliable elevation information is of great value to emergency personnel safety and UAV applications. The global navigation satellite system (GNSS) is not reliable in the environment where signals are blocked, such as forests and urban canyons, and even cannot be located in indoor or underground spaces. Method: To resolve the problems of low elevation positioning accuracy of GNSS and discontinuous elevation information in indoor space, this paper integrates two kinds of sensors, GNSS and barometer, which do not depend on local ground infrastructure, and adopts robust Kalman Filter to realize continuous elevation estimation and floor identification in indoor and outdoor space. Result: The experiment shows that the GNSS/ barometer fusion can realize the continuous estimation of indoor and outdoor space elevation, the accuracy of elevation estimation can reach sub-meter level, the accuracy of floor identification can reach 100%, and the estimation error of height difference between floors is 0.504 meter. Conclusion: The GNSS/barometer fusion method proposed in this paper can realize continuous elevation positioning in indoor and outdoor space with strong robustness, it may meet the requirements of some location services for elevation information.