Abstract: The invention relates to a coordinate detecting method for a touch panel. Firstly, a plurality of X-axis and Y-axis I/O ports are converted to a plurality of X-axis and Y-axis scanning wires respectively by orthogonal method. Polling signals are transmitted to X-axis I/O ports, and are transmitted to the X-axis scanning wires. According to the polling signals, a plurality of X-axis detection signals are stored. A largest X-axis detection signal and a second largest X-axis detection signal are determined by compared method so as to calculate a X coordinate position of the sensor pen touching the touch panel. The steps are repeated to calculate the Y coordinate position of the sensor pen touching on the touch panel. According to the coordinate detecting method of the invention, the number of the I/O ports can be reduced, and the resolution of the touch panel can be improved.