A data transmitting and receiving device and method are used for saving powers and maintaining the connection quality, stability and continuous link. The method includes the step of gradually adjusting the de-emphasis of the signal transmitted from the data transmitting and receiving device according to the setting value thereof. The method also includes the steps of transmitting training sequence signal with an amplitude and the default de-emphasis by the data transmitting and receiving device to the remote device, receiving the training sequence signal from the remote device, thereby the channel attenuation is estimated using the method, and a better de-emphasis is set up. Then, the data transmitting and receiving device gradually increases the amplitude of the training sequence signal and re-transmits it until the remote device receives the training sequence signal transmitted therefrom.