  The Coulomb barrier and electron screening cause difficulties in directly
measuring nuclear reaction cross sections of charged particles in astrophysical
energies. The Trojan-horse method has been introduced to solve the difficulties
as a powerful indirect tool. In order to understand experimental spectra
better, Geant4 is employed to simulate the method for the first time. Validity
and reliability of the simulation are examined by comparing the experimental
data with simulated results. The Geant4 simulation can give useful information
to understand the experimental spectra better in data analysis and is
beneficial to the design for future related experiments.
