Micro-Doppler (m-D) in ballistic targets is characterized by applying an important means to warhead recognition. However, when the micromotion of the ballistic targets is accompanied by macromotion, the timefrequency representation is no longer a sinusoidal modulation curve. Aimed at the problem that the microDoppler feature extraction method based on the sinusoidal hypothesis of timefrequency representation may become ineffective, an estimation algorithm based on circular autocorrelation function (CACF) in combination with the circular average amplitude difference function (CAMDF) is proposed to obtain the circular coefficient matrix of timefrequency representation and average circular coefficients of the matrix, estimating the mD period of ballistic targets. The algorithm does not need to assume with the target macromotion having been accurately compensated and the shortcomings of traditional mD period estimation methods having been overcome effectively. The feasibility of the algorithm is demonstrated by theoretical derivation, and the effectiveness and antinoise of the algorithm is verified by simulation experiments.