Different from traditional sensor, FBG sensor has particular detective probe length in different angle of sensor because the sensitivity of FBG in axial direction is much better than other directions. Thus the layout angle of FBG sensor can affect the performance of FBG sensor network greatly. A detection model is proposed for FBG sensor which fits its feature based on probability model, and the correctness of the model is verified by experiment. Then particle swarm optimization algorithm is used to optimize the placement of FBG sensor network. Finally, the results of optimization method are compared with those of optimization method not considering the layout angle of sensor. It is indicated that the performance of sensor network is greatly improved by considering the layout angle in placement.