Cross-range scaling for ISAR image is the basis of target’s structure feature extraction,and the key point is the estimation of its rotate speed. Firstly,the vectors which are composed of target’s scattering points in ISAR image are obtained based on ballistic target’s ISAR sequence. Secondly,the expression is estimated by using the rotate angle,and the maximum modulus vectors’ rotating angle between ISAR sequence is mapped to target’s rotating angle. Then,the estimation of target’s rotate speed is achieved. At last,the performance of the method is analyzed. This method takes full advantage of the characteristics of ISAR image sequence and target’s feature information,and it avoids the complex image registration and complicated echo Doppler rate estimation. Simulation results show that the method can estimate target’s rotate speed efficiently and have a low scaling error.