Abstract: To deal with the problem of optimal sensor placement in truss structures, a sensor optimal placement method is proposed with the graph theory and traveling wave mechanics as the goal to maximize the damage sensitivity, according to the propagation characteristics of traveling waves in truss structures. Established was the mapping relationship between the truss members and nodes with the edges and nodes of graph theory, and extended was the breadth search method of graph theory to consider the scattering and reflection characteristics of traveling wave along the nodes in truss structures, thus obtained was the propagation path of wave traveling in the truss structure. Through the analysis of traveling wave dynamics, calculated are the transmission coefficients of traveling waves of various node connections, and then combined with the propagation path, acquired are the sensitivity coefficients of all nodes to the vibration caused by traveling waves in the same time. Calculated upon the sensitivity coefficient was the sensitivity total value matrix, and found out was the most sensitive excitation point and sensor placement point of each member. Simulation model and experimental truss results show that: the sensor placement position obtained by the method proposed is most sensitive to damage; provides a new way for the optimal placement of sensors in large truss structures.