Aiming at the problem of bar identification in image,A new method of bar segmentation and identification for marking watershed is proposed.This method c ombines the distance transformation and gradient reconstruction to define the marking points ,and uses watershed transformation to complete bar identification.Firstly,the low-frequ ency part of the bar image is used to automatically extract the threshold,and the local extreme poin ts in the distance map corresponding to the area are screened.Extract the local extremum region co rresponding to the low-frequency component in the bar image and combine the local extremum to obtain the foreground mark.Then the watershed is transformed based on the foreground marke r,and the ridge line obtained by the watershed transformation is used as the background ma rker.Finally, after the gradient reconstruction,the bar image is the gradient-based watershed based on the marker to obtain the bar segmentation recognition result.In this paper,we comb ine the distance graph to select the marker point and add the exact number of bars,and solve the over-segmentation problem in the target recognition of watershed algorithm eff ectively.On the other hand,the advantages of accurate edge location after watershed transformation of gradient image are preserved,and the complete bar profile is obtained.Experimental results show t hat this method satisfies the real-time,robustness and accuracy requirements of image recognit ion,and can be applied to the recognition of quasi circle target and related fields.