One-dimensional dual-electron model for CO2 is suggested on the basis of the electron configuration. Time-dependent Schrdinger equation is numerically solved by deploying symmetric split-operator technique for high-order harmonic generation (HHG) spectra of the CO2 model that is exposed to 800 nm wavelength laser pulses. The computed results show that the present model for CO2 is moderate for computational load, and is able to elucidate the HHG characteristics. Laser pulse parameters play an important role in HHG, and the multi-cation nature of molecule may be responsible for the destructive interference in HHG spectra.