A variety of QoS guarantee is to be needed in the real-time transmission of video stream in wireless multimedia sensor networks. A multi-path routing algorithm ACMRA (ant colony based multipath routing algorithm) based on improved ant colony algorithm is proposed in this paper to find the paths set which includes paths according to different priorties. It also takes the importance of video data into consideration when making path choice. The improved ant colony algorithm enjoys faster finding and convergence speed by optimizing the initial distribution of artificial pheromone on network link. By introducing the multi-path mechanism throughput, the network and video transmission performance are both enhanced, while it also balances network resources and prolongs the network life cycle. Compared with the other classic routing algorithm, the experimental results illustrate that ACMRA has obvious advantages in terms of raising network, video transmission performance, and extending the network life cycle.