This paper presents a new method for ionospheric height estimation with High Frequency Surface Wave Radar. Ionosphere, usually sounded by specialized equipment, is of great significance for radar system and other electromagnetic systems. Without ionosonde, the ionospheric parameters can only be obtained from the theoretical or empirical model, which, however, is incapable of properly delineating the ionospheric current state. The bad steerability of High Frequency Surface Wave Radar's vertical directional diagrams will cause the ionosphere reflected echoes also be received, which could provide ionospheric information. The target's reflection of ionosphere and echoes along the sea surface will form a multipath propagation model, through which the ionospheric height could be estimated. In this paper, ionospheric height estimates will be obtained by fixed island's multipath echoes and then be verified by comparing with the predictions of International Reference Ionosphere.