A data transmitting device capable of configuring different operating frequencies for use by a tire pressure monitoring detector includes: a standard oscillator; a phase locked loop including a phase frequency comparator, a filter, and a pressure-controlling oscillator; 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. The microcontrol unit allows a user to select and send the first or second ratio to the phase frequency comparator. The phase locked loop generates a target frequency signal according to the first or second ratio selected by the user. 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.