Wireless Multimedia Sensor Networks (WMSNs) is comprised of video sensor, digital signal processing unit and digital radio interface. Owing to ubiquitously retrieve multimedia content such as video and audio streams, still images, and scalar sensor data from the environment, the Quality of Service(QoS) problem of WMSNs becomes a hot research. In this paper, we will discuss the parameters for QoS performance evaluation, classify some typical protocols which proposed in the literature both at home and abroad, give a comprehensive description of these algorithms or protocols, and compare them from the aspects of layered architecture, communication model, energy efficiency, etc. Finally, the paper also concludes with a discussion on the future directions and challenges in the areas of QoS routing in WMSNs.