The detailed evolution process of the electromagnetic pulse signal, especially the change information of its steep front, is helpful to deeply understand the generation and propagation process of the electromagnetic pulse signal. It has extremely important scientific and practical significance for the development of our national defense and natural science. In this work, a compressed sensing technology of analog signal based on three parallel low-speed analog-to-digital converter (TPL) is proposed. By under-sampling the electromagnetic pulse signal (the sampling frequency of the signal is lower than the requirement of Nyquist sampling theorem), the high-speed acquisition waveform of the measured electromagnetic pulse signal can be obtained and recovered. Based on the application of TPL compressed sensing technology, the requirement of the measured electromagnetic pulse signal on the sampling rate of the back-end electronic ADC can be reduced. In this paper, the methods of establishing sparse dictionary, observation matrix and signal reconstruction in the process of TPL implementation are deeply studied, and an atomic number adaptive dictionary construction method based on KSVD is innovatively proposed. On this basis, the compressed sensing effect of TPL system on electromagnetic pulse signal is tested by simulation and experiment, which verifies the feasibility of this method.