Gelled propellant simulant containing 5 wt% carbon particles with an average diameter of 5 μm was prepared, and the atomization characteristics was investigated. The rheology properties of the simulant were measured. Under the conditions of jet velocity of 10-22 m·s^-1, impingement angle of 60°-90°, injector orifice diameter of 0.5-1.5 mm and ratio of injector orifice length to diameter of 3.5-8, atomization experiments were carried out. The breakup characteristics of liquid sheet were studied by the linear stability theory. Results show that the addition of carbon particles makes the simulants consistency coefficient increase and flow index decrease. Within the investigation conditions, the simulant is atomized into ligaments and large drops, and the atomization quality improves with the increases of jet velocity and impingement angles. The changes in ratio of injector length to diameter and the injector orifice diameters have little influences on the atomization patterns. The relative error between the predicted breakup lengths and measured values is about 14.9%-24%, but the tendency of the breakup lengths predicted by the linear stability theory agrees well with the experimental results.