A message transmission method includes steps of receiving a identifier of a first wireless transmitter by a first portable device; transmitting associative message of the wireless transmitter by the first portable device; retrieving the identifier of the targeted wireless transmitter according to the identifier transmitted by the first wireless transmitter; linking the associative message of the wireless transmitter with the identifier of the targeted wireless transmitter; verifying the identifier of the targeted wireless transmitter with a identifier transmitted by a second wireless transmitter and received by a second portable device to confirm whether the identifier is the same or not; and if the identifier is the same, the second portable device retrieves wireless transmitter associative message which is associative to the identifier of the targeted wireless transmitter for later application.