Abstract: Network coding greatly improves the throughput in multi-radio wireless mesh networks (MR-WMNs), however, it also increases the multicast transmission delay due to packets buffering during the coding/decoding procedure. In order to optimize multicast transmission delay, it is crucial to quantitatively analyze key parameters affecting the performance of WMNs. An average multicast transmission delay (AMTD) optimization scheme is proposed based on modeling and analysis of MR-WMN multicast transmission delay using network coding. Firstly, we propose a multi-radio multicast model consisting of M/M/Nr and GI/GI/1 queueing systems in tandem. Secondly, we analyze the features of multicast transmission delay based on the proposed model, and obtain the quantitative relationship between AMTD and network parameters by computing the sum of average waiting time of two queueing systems. Finally, theoretical analysis and simulation results show that the parameters among network load intensity, channel quality, multicast group size, network coding size and RF allocation ratio, can be used to optimize the average multicast transmission delay. The conclusion is given that the best ratio with lowest delay may not still hold within different network coding sizes for a given network and the average multicast transmission delay optimization can be achieved by adjusting RF receive/send ratio suggested by the AMTD formula.