In this paper, we use the Monte-Carlo method to study the reaction of the electron-hole pairs produced to
randomicity and the statistics rule, according to the principal of the detector and the gamma ray track in the CdZnTe
detector. The EGSnrc software based on Monte-Carlo method is used to simulate the process of carriers' transportation.
The statistics rule greatly reflects the result in Monte Carlo simulation. Firstly, we use Ansys software to create a model
of the object for Monte-Carlo simulation, which is the basis for our further Monte-Carlo research. During Ansys
simulation, a columniform block is created, where the electrical and thermal properties of the materials for simulation
use are established. Then, the charge collection efficiency through the statistical approach was calculated using the
EGSnrc software. Furthermore, by considering the interaction mechanism of CdZnTe with gamma ray, several modules
in the software are added into Monte Carlo simulation. Finally, the pulse height spectra with the response to gamma ray,
are available from the simulation. The comparison between the simulation and the measurement result is indicated,
which shows that the simulation experiment is reliable. The Frisch grid detector can get the responses more efficiently
than other structure devices.