To ensure the time determinability of avionics applications based on Commercial-off-the-shelf (COTS) platform when accessing into AFDX (Avionics Full Duplex switched ethernet ) network,an AFDX real-time flow middleware was designed .Using protocol conversion function based on filtering mechanism of intermediate driver,the middleware achieved communications between networks running with different protocol . Core code of frame sequence number (SN) insertion was described .A time scheduling algorithm which has the minimum jitter aimed at VL-Multiplexing was proposed,by distributing the sending-time of visual links ( VL),it is able to avoid contention on a rate limited physical link .Finally,experiments were made to test the performance of AFDX real-time flow middleware and the results showed that:the middleware model achieved the format mutual conversion between TCP/IP protocol and AFDX protocol,and the time scheduling algorithm can decrease jitter caused by VL multiplex apparently,which ensured the time determinability of AFDX communication .% 为保证COTS平台下的航空电子应用在航空电子全双工以太网（ AFDX）上的时间确定性接入，设计了AFDX网络实时流量的中间件接入模型。通过基于中间层驱动过滤机制的协议转换，实现了双边网络的协议对接，并给出了帧顺序号（ SN）的插入方法；通过对虚拟链路（ VL）在时间上进行有效分配，避免了速率受限的数据流对物理链路的争用，在实现单条VL的BAG整形基础上提出了使实时流量抖动最小的VL复合时间调度算法。搭建典型实验环境对该模型进行仿真实验，结果表明，中间件模型能准确地实现数据帧TCP/IP协议与AFDX协议格式的相互转换，且该时间调度算法大大减小了VL复合所产生的抖动，保证了数据流传输的时间确定性。
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