Motion Estimation (ME) palys a crucial part in frame rate up-conversion (FRUC) and video compression. One popular chip estimator, 3-D Recursive Search (3DRS), has achieved success in nowadays high definition televisions(HDTV). However, for future ultra high definition television (UHDTV) applications, the amount of computation increases exponentially. Therefore, there is an urgent need for further computational reduction. In this paper, we propose an effective early termination (ET) technique to reduce the calculation of absolute difference (AD), which is the most computation-intensive process in ME. First, motion vector (MV) candidates are examined in an adaptive search order (ASO) of their reliability to be true estimator. Then, the ET method dynamically changes the threshold for different motions to terminate accurately among reliable candidates. From the simulation, we can achieve an average computation reduction by 42% (up to 65%) with a slight PSNR degradation of 0.16dB on average.