Disclosed is a terahertz time domain spectrum data acquisition system, comprising: a lock-in amplifier (11), a pre-amplifier (12), an active filter (13), an attenuation amplifier (14), an analog-to-digital converter (15) and a digital-to-analog converter (16) connected in sequence, wherein the lock-in amplifier (11) is used to amplify a weak current signal generated by a photo-conductive receiving antenna and output a first weak voltage signal; the pre-amplifier (12) is used to compensate for the amplifying power of the lock-in amplifier (11) and amplify the first weak voltage signal to obtain a second weak voltage signal; the active filter (13) is used to carry out low-pass filtering on the second weak voltage signal and then amplify same, so as to obtain a third weak voltage signal; the attenuation amplifier (14) is used to convert the third weak voltage signal into a fourth weak voltage signal; the analog-to-digital converter (15) is used to acquire the fourth weak voltage signal and convert same into a digital voltage signal; and the digital-to-analog converter (16) is used to convert the digital voltage signal into an analog voltage signal. The terahertz time domain spectrum data acquisition system uses a design of a single board to realize terahertz time domain spectrum data acquisition, has the characteristics of being small-sized, fast and easily integrated, and has relatively strong usability and practicability.