A data transmission method includes: transmitting a plurality of first transmitting signals from a plurality of transmitting areas of the first touch device; determining, by the second touch device, whether a first sensing signal corresponding to the plurality of first transmitting signals is received; if yes selecting, by the second touch device, a receiving area in a first overlap range according to signal intensity of the first sensing signal; transmitting a second transmitting signal from the receiving area; determining, by the first touch device, whether a second sensing signal corresponding to the second transmitting signal is received; if yes, selecting, by the first touch device, a first transmitting area in a second overlap range from the plurality of transmitting areas according to signal intensity of the second sensing signal; determining a final transmitting area and a final receiving area; and performing a data transmission process.