The present invention relates to a system and to a method for QoS (Quality of Service) support in a ubiquitous sensor network. The system for QoS support in a ubiquitous sensor network includes a mesh coordinator and nodes. The mesh coordinator organizes a super frame containing a dedicated QoS data transmission period, and synchronizes each of the nodes constituted into one network with the abovementioned super frame. The nodes create a beacon frame containing information on whether or not to set QoS, to broadcast the beacon frame in a dedicated beacon period of the super frame if QoS data transmission is needed, to create a QoS data frame with a set priority, and to transmit the QoS data frame to the dedicated QoS data transmission period of the super frame in the case of transmitting QoS data. The present invention divides QoS data from general data to improve the quality of data transmission and ensure stability, and prioritizes QoS data to transmit the most important data among QoS data in a quick and stable manner.