Digital image synthesis (DIS) is a specific counter-ISAR technique which employs a false target synthesized to deceive the imaging radar. To make the synthesized false missile images more actual, the distribution of the scattering centers for the according false object must be similar to the real-time ISAR images of a true BM over the whole trajectory. This paper presents a novel process to synthesize the images along the trajectory which is used as the false target to be synthesized. The kinematic model of the BM is developed firstly and the trajectory is calculated based on such a model. Then the RCS of the BM as a function of the flight time is calculated and the time-dependent ISAR image sequences along with the trajectory are formed. The real-time ISAR images of a ballistic target along its trajectory being used in false image synthesis can improve the counter-ISAR capability of the DIS