The invention provides a digital analogue converter and a source driving circuit. In the invention, a harmonic signal is generated through a harmonic generator and sampled through a sampling unit; therefore, conversion from a digital signal to an analogue signal is realized; the digital analogue converter is simple in structure; the occupation area can be effectively reduced; the power consumption can be reduced; and thus, the source driving circuit adopting the digital analogue converter can be applicable to a flat-panel display having relatively high resolution.