The invention discloses a component symbol detection and recognition method in an electrical engineering drawing. The method comprises the following steps that: 1) carrying out binarization processing and denoising processing on the image of an original electrical engineering drawing; 2) adopting Hough Transform, an image filling means based on a regional factor and open operation processing on the processed image, and detecting and extracting the position of a component in the image; 3) through the thought of a connected region, classifying the components through the thought of the connected region, traversing the image, judging the size type of each component through the center of gravity, and identifying the component; and 4) finally, through a similarity recognition method and an image boundary circle detection method, identifying the identified component. Through the relevant knowledge of digital image processing and pattern recognition, the components in the electrical engineering drawing can be detected and recognized, the method can be applied in a similar topic through little revision, and therefore, the method has a certain instructive meaning for other research fields.