H.264/AVC is the latest video coding standard from ITU-T. It provides superior and efficient video coding at low bit rates. Flexible macroblocks ordering (FMO) is an error-resilient tool included in H.264/AVC. In this paper, we present an improved three-dimensional flexible macroblock ordering, (3D FMO), which is also designed to be H.264/AVC compatible. With our 3D macroblocks allocation map, simulation results have shown the 3D FMO works better with the error concealment tool in H.264/AVC. Simulations also show a PSNR gain of about 1-2dB for IP-based broadcast video application for 10% packet loss. Better video transmissions qualities are achieved, especially under lossy transmission channels such as wireless networks.