The hierarchical B-picture coding is introduced into the extension of H.264/AVC in order to improve coding performance and provide strong temporal scalability as well. In general, coding performance is affected by the content variation in GOP. Therefore, the ways to determine the size of GOP (Group of Picture) is a critical problem for video coding. In this paper, the adaptive GOP structure determination scheme is proposed to select the appropriate GOP size with content complexity consideration. Experimental results show that the proposed method can provide better PSNR performance compared to the highest GOP setting in the existing hierarchical B-picture coding of H.264/AVC.