The invention discloses a 
traffic sign detection method in automatic driving based on a YOLOv3 network, and belongs to the field of 
traffic sign detection. The method solves the problems that an existing YOLOv3 network target detection 
algorithm is not high in detection precision and the detection speed cannot meet the real-time requirement. According to the invention, an improved 
loss function isprovided, so that the influence of a 
large target error on a 
small target detection effect is reduced, and the detection accuracy of a small-size target is improved. An improved 
activation function is provided, a negative value is reserved, meanwhile, changes and information propagated to the next layer are reduced, and the robustness of the 
algorithm to 
noise is enhanced. The real frames in thetraffic sign 
data set are clustered by using a K-means 
algorithm to realize the pre-fetching of a target frame position and accelerate convergence of the network. The detection precision mAP of the 
traffic sign detection model on a 
test set reaches 92.88%, the detection speed reaches 35FPS, and the requirement for real-time performance is completely met. The method can be applied to the field of 
traffic sign detection.