Recently, the necessity of parallel ultra-high definition (UHD) video processing has been emerging, and the usage of the computing systems that have asymmetric processors, such as ARM big.LITTLE, is actively increasing. Thus, a new parallel UHD video processing method optimized for asymmetric multicore systems is essential. This paper proposes a novel High Efficiency Video Coding (HEVC) Tile partitioning method for the parallel processing by analyzing the computational power of asymmetric multicores. (1) The proposed method analyzes the computing power of asymmetric multicores and (2) the regression model of computational complexity per video resolution. Lastly, (3) the model determines the optimal HEVC Tile resolution for each core and partitions and allocates the Tiles to suitable cores. Experimental results with the test sequences of common test condition (CTC) show that the decoding speed improved by 17 % with implemented multi-threading module on ARM asymmetric multicore systems.