Abstract: The current-mode-counting measurement method was proposed to overcome the shortcomings of traditional counting system with Si-PIN detector such as relatively low count rate and the inconvenience of time information measurement of particles in low intensity pulsed radiation measurement. In the method, the pulse generated by Si-PIN detector as induced by incident particle was amplified linearly and then digitized at high speed, and the spectrum was acquired by digital signal processing algorithms with the waveform data. The current-mode-counting measurement system was developed with Si-PIN detector, current-sensitive preamplifier and wideband digital oscilloscope. Experiments were carried out with ²⁴¹Am-²⁴⁴Cm and ²³⁹Pu sources, and spectra and time distributions of incident α-particles were acquired. The energy resolution of spectra was enhanced by FIR and IIR digital filters in data processing. The count rate is up to 2×10⁶ s^-1, and the system is suitable for the measurement of low intensity pulsed radiation field.