Solid oxide fuel cells (SOFC) has attracted considerable attention in recent years as a power conversion system, owing to its high-energy conversion efficiency, fuel flexibility and low pollution emissions as well. Recently, the intermediate temperature-solid oxide fuel cell (IT-SOFC), which operates at lower temperatures (600~800 °C) to reduce cost and to improve efficiency, appears to be an alternative choice for the development of SOFC. La_0.8Sr_0.2Ga_0.8Mg_0.2O₃ (LSGM), with a perovskite structure, presents a high ionic conductivity at intermediate temperatures. However, the common methods to fabricate the LSGM electrolyte (e.g., solid state method) often lose their advantages owing to the depletion of Ga and the interfacial reaction between the LSGM and electrodes. Vacuum cold spray (VCS), based on the impact adhesion of fine particles to build up ceramic film at room temperature, is a new and promising method to fabricate thin (﹤20 mm) and dense (LSGM) electrolyte membrane. In the present study, the LSGM electrolyte layer with a thickness of ~10 mm is prepared by a home-developed VCS system assisted with in-situ particle heating approach (25~400 °C). The output performance of cells assembled with VCS-LSGM is determined at 500~750 °C. Results show that the OCV value is above 1.0 V, suggesting that the VCS-LSGM electrolyte is dense enough for the application to SOFC. Meanwhile, the ionic conductivities of LSGM coatings prepared by different in-situ particle heating temperatures were determined by an electrochemical impedance spectroscopy system. In addition, the microstructure and phase structure of LSGM coatings was characterized by scanning electron microscopy and X-ray diffraction. Based on this study, it is possible to conclude that the VCS is a promising method to prepare the LSGM electrolyte applied in the IT-SOFC.