A novel expandable graphite (EG) particles were initially used for in-depth steam channeling control in heavy oil reservoirs. Compared with natural graphite (NG) particles, EG particles have a special intercalation structure, which makes it possible to expand normally at the steam-temperature conditions. The morphology results show that EG particles are oval or circular with micron-size distribution at the initial stage but that the structure changes into a worm-like structure when aging at high temperatures. The higher the temperature, the easier the EG particles will expand. By adding polymer into the EG particle system, the particle suspension performance is improved. Based on the sand-pack flowing experiment, EG particle system with high concentrations generally exhibits powerful steam channeling control capacity. The EG particles could effectively expand and form a worm-like structure during steam injection in heavy oil reservoirs. The expanded EG particle can effectively control steam channel by directly plugging pore throat or becoming retained in high permeability steam channels, which could divert the injected steam into low permeability zones. These EG particle systems may be an alternative used for steam channeling control in other similar steam injection heavy oilfields.