A data transmitting device capable of configuring different operating frequencies for use by a tire pressure monitoring detector, comprising: a standard oscillator for providing an oscillation signal of a fixed frequency and using the fixed frequency as a standard frequency; a phase locked loop comprising a phase frequency comparator, a filter, and a pressure-controlling oscillator, with the phase frequency comparator being electrically connected to the standard oscillator, the filter being electrically connected to the phase frequency comparator, and the pressure-controlling oscillator being electrically connected to the filter, wherein the pressure-controlling oscillator has an output end electrically connected to the phase frequency comparator; a microcontrol unit electrically connected to the standard oscillator and the phase frequency comparator and adapted to store a first ratio and a second ratio; and a signal output unit electrically connected to the output end of the pressure-controlling oscillator and the microcontrol unit, wherein the microcontrol unit allows a user to select the first ratio or the second ratio and sends the first ratio or the second ratio selected by the user to the phase frequency comparator, wherein the phase locked loop receives an oscillation signal from the standard oscillator, generates a target frequency signal (Ts) according to the first ratio or the second ratio selected by the user, and sends the target frequency signal (Ts) from the output end to the phase frequency comparator and the signal output unit, wherein the microcontrol unit sends a data to the signal output unit, and the signal output unit outputs the data according to the frequency of the target frequency signal (Ts) characterized in that the signal output unit further has a variable impedance antenna and is configured to adjust impedance of the variable impedance antenna according to frequency of the target frequency signal (Ts) sent from the output end of the pressure-controlling oscillator, so as to match the frequencies, thereby sending out wirelessly the data through the variable impedance antenna according to the frequencies. a standard oscillator for providing an oscillation signal of a fixed frequency and using the fixed frequency as a standard frequency; a phase locked loop comprising a phase frequency comparator, a filter, and a pressure-controlling oscillator, with the phase frequency comparator being electrically connected to the standard oscillator, the filter being electrically connected to the phase frequency comparator, and the pressure-controlling oscillator being electrically connected to the filter, wherein the pressure-controlling oscillator has an output end electrically connected to the phase frequency comparator; a microcontrol unit electrically connected to the standard oscillator and the phase frequency comparator and adapted to store a first ratio and a second ratio; and a signal output unit electrically connected to the output end of the pressure-controlling oscillator and the microcontrol unit, wherein the microcontrol unit allows a user to select the first ratio or the second ratio and sends the first ratio or the second ratio selected by the user to the phase frequency comparator, wherein the phase locked loop receives an oscillation signal from the standard oscillator, generates a target frequency signal (Ts) according to the first ratio or the second ratio selected by the user, and sends the target frequency signal (Ts) from the output end to the phase frequency comparator and the signal output unit, wherein the microcontrol unit sends a data to the signal output unit, and the signal output unit outputs the data according to the frequency of the target frequency signal (Ts) characterized in that the signal output unit further has a variable impedance antenna and is configured to adjust impedance of the variable impedance antenna according to frequency of the target frequency signal (Ts) sent from the output end of the pressure-controlling oscillator, so as to match the frequencies, thereby sending out wirelessly the data through the variable impedance antenna according to the frequencies.