For studying the statistical character of the random signal, the width and amplitude of two relatively independent characteristic parameters are used to establish the two-parameter pulse model of the random signal. On the basis of this, the counting distributions of random signal for aerosol’s scattering pulse and background noise of photoelectric sensor are statistically analyzed by using the high-speed data acquisition card PCI-9812. The experimental results show that the counting distributions of amplitude and width subsets for the random pulse signals match well with the form of the lognormal distribution while using the natural number as the independent variable. Further more, the calculating results indicate that the amplitude and width of the distribution have nonlinear transform relation in the field of definition of them for pulsed signal. Namely, the two parameters' statistical distributions have the fractal character with non-integral dimension.