Abstract: Volcanic activity is closely related to deep magma transportation and material melting state. Long-term dynamic monitoring of volcanoes is helpful to master their deep structure and variation characteristics, and provides important geophysical evidence for predicting volcanic eruptions and volcanic earthquakes. We selecte the observation data from May 2018 to April 2019 for inversion, and the data come from a long-term magnetotelluric observation station set up by Phoenix Company in the Big Island, Hawaii. We obtain the deep electrical structure below the observation point and its time-varying characteristics, and compare the inversion results with the previous exploration results. The research results show that there is an obvious thin low-resistance layer at a depth of 2−3 km below the observation point, and its resistivity is about 20 Ω·m. It is speculated that it may be a magma chamber developed in the shallow part of the Earth’s surface. The range of resistivity at the depth of 100 km is 20−70 Ω·m. It is speculated that there may be an active complex magma reservoir at this depth. The inversion results are comparable with the previous exploration results in neighboring areas.