The invention discloses a detector layout method in a city traffic signal control system including the following steps: 1) identifying the type of highway, main way, secondary way, and slip way, 2) identifying the type of strategic, tactical, general and sensitive intersection, 3) determining the type, size, number of strategic, tactical, sensitive detectors of the entire city, and location and quantity of the corresponding detectors laid in various types of roads, 4) installing the strategic, tactical and sensitive detector, and linking them and other equipment with wire or cable, 5) installing the detector to detect bicycle flow on the bicycle Lane, and linking it and other equipment with wire or cable.