Detection of electronic components pins is an essential part during assembling the printed circuit board，therefore，an accurate and fast method is needed to determine the subtle differences between qualified and unqualified pins. To detected the number，size and spacing of vertical capacitor pins，the features of vertical capacitor pins were considered and the area and circularity characteristics of connected region of binary image were analyzed to eliminate the interference of image noise and to locate the targets accurately.The results of the contrast test and stability test demonstrate the 〖BF〗method’s〖BFQ〗 high accuracy and high speed，and it can meet the requirements of online detection of electronic components pins.