Abstract: Accurate determination of the ionospheric real-time state plays an important role in radiowave information systems such as modern communication and satellite navigation system. To provide three-dimensional(3D) specification of the ionosphere electron density for current conditions, a new 3D ionospheric electron density reconstruction method is developed by data ingestion of ground-based global navigation satellite system(GNSS) and constellation observing system for meteorology, ionosphere and climate(COSMIC) occultation measurements. Based on the latest International Reference Ionosphere model (IRI-2016), IG index and Rz index of IRI-2016 are selected as the driving parameter. With Brent algorithm, optimal IG and RZ indices are obtained in two steps by data ingestion of ground GNSS and COSMIC occultation measurements. The comparison between reconstructed results and data of eight ionosonode stations in the European region indicates that the absolute mean error and standard deviation of the reconstructed ionospheric N_mF₂ were decreased by 33% and 29% respectively, while the reconstruction error of the ionospheric h_mF₂ decreased by about 55% and 30% respectively. Comparison results demonstrate the accuracy and effectiveness of the proposed method.