A principle and method of constructing the digital acquisition system is presented in this work,which is convenient for the study on the theories and algorithms of digital nuclear signal processing.The hardware system of the digital acquisition system consists of front-end controller,waveform digitizer and PC workstation,on which the software system has been developed based on Visual C++under Windows environment.The alterable-frequency sampling(AFS)algorithm and the alterable-frequency trapezoidal filter(AFTF)algorithm have also been studied in the real-time environment,along with a digital nuclear spectrum acquisition system being set up based on the new algorithms and theγ-ray spectra of 241Am being shown.A useful experimental platform could be provided by this work for the successive work such as the development of global digitized nuclear measurement system and the study of digital nuclear signal processing. A principle and method of constructing the digital acquisition system is presented in this work, which is convenient for the study on the theories and algorithms of digital nuclear signal processing. Hardware system of the digital acquisition system consists of front-end controller, waveform digitizer and PC workstation, on which the software system has been developed based on Visual C ++ under Windows environment. The alterable-frequency sampling (AFS) algorithm and the alterable-frequency trapezoidal filter (AFTF) algorithm have also been studied in the real- time environment, along with a digital nuclear spectrum acquisition system being set up based on the new algorithms and the γ-ray spectra of 241Am being shown. A useful experimental platform could be provided by this work for the successive work such as the development of global digitized nuclear measurement system and the study of digital nuclear signal processing.