The invention discloses a signal excitation and data acquisition device and method used for magnetic induction tomography. The signal excitation and data acquisition device includes a transmitting-receiving coil Tn (T1-Tn), a transmitting-receiving switch T/R, a multi-way switch MUX, a power amplifier PA and a low-noise amplifier LNA, a signal generator, a 0/90 phase shifter, a frequency divider, an analog-to-digital converter A/D, reference voltage and a controller MUC, wherein the power amplifier PA is connected with the output end of the signal generator. According to the signal excitation and data acquisition device and method used for magnetic induction tomography of the invention, unitary excitation signals are adopted, and are adopted as sampling clock of the analog-to-digital converter; a zero intermediate frequency mixing function can be directly completed through utilizing the analog-to-digital converter; a single-way time division orthogonal analog and digital sampling method is adopted to complete the phase detection of the excitation signals and detection signals; a simple digital method is adopted, analog-to-digital conversion data rate can be decreased, namely, synchronous frequency-decreased sampling can be realized.