Video data compression is one the core technologies of video conference, which aims to enable significantly high performance data coding. In order to achieve this, a robust rate-distortion optimization (RDO) technique is needed to be employed to select the best coding mode This paper presents optimization solution about inter prediction mode decision algorithm of H.264/AVC for video conference under the HLA/RTI framework. Our objective is to reduce the computational complexity of the CODEC (Coder & Decoder) with insignificant rate-distortion performance degradation. I. PREFACEHLA is a brand-new field, which is put forward less than 4 years. In order to track new technology abroad in time, we take the lead in the realization of distributed interactive simulation platform based on HLA/RTI standard, called YinHe High Performance Distributed Simulation System. It is a development platform for large-scale synthetic simulation with multiple systems, which can widely gain applications in aerospace, aviation, and various national defense constructions. What's more, it is applied in weapon development simulation (single system simulation), weapon countermine simulation (multiple system simulation), combat training simulation of different class (large-scale simulation with multiple systems) and other fields. It is useful to shorten the period of experiment and development, improve quality and save the funds, which is of importance for China's national defense infrastructure and economic development.Video conference is not a new concept, and it has appeared by nearly half a century ago and still continues to evolve. Since the earliest video conference system, the industry of video conference today has topped a higher level than ever before through the long-lasting development and maturity.Multi-person video communication system based on high level architecture (High Level Architecture, HLA) uses distributed interactive simulation system. It shows superiority and advancement compared with similar software in flexibility, interactivity, extension, reusability, and many other aspects.As a new video coding standard, H.264/AVC absorbs merits of current video coding standard. At the same time, it puts forward many new ideas and algorithms, which substantially improves the coding efficiency and image quality. The statistic results show that compared with H.263+ or simple configuration of MPEG4, H.264/AVC can save nearly 50% of the coding rate under the same image quality [1].During the video conferencing, characteristics of video frame are that in the entire video, the picture is simple and with few changes; in particular, the background remains almost the same; only a few objects (including people) have some simple motion changes, such as translatory motion, rotation or speaking.This paper puts forward optimization solution about inter-frame prediction algorithm of H.264/AVC for video conference under the HLA / RTI framework. II. INTERACTIVE PRINCIPLES OF HLA/RTIHLA adopts Object Model to federate various exchangeable data and re...