In this paper, we presents an efficient algorithm for early detecting all-zero discrete cosine transform (DCT) coefficient blocks (AZB) by combining Parseval energy conservation theorem and the successive elimination algorithm (SEA). A mathematical inequality is derived from Parseval theorem and applying SEA for motion estimation. The simulation results show that the proposed algorithm achieves approximately a 12%~22% computational saving compared to the existing methods. Furthermore, when the proposed algorithm is implemented with other fast detection algorithms, it can further improve AZB detection ratio without any video-quality degradation.