Enhancement of nonlinear chirped frequency on electron-positron pair creation in the potential well is studied by the computational quantum field theory. The density, number and energy spectrum of electrons created under a single oscillating potential well and combined potential wells are investigated. The frequency spectrum and instantaneous bound states are also analyzed. It is found that nonlinear chirp effect is more sensitive to the low frequency region. When appropriate chirp parameters are selected, compared with the fixed frequency, the number of electrons created under combined potential wells can be increased by 2 to 3 times. For a single oscillating potential well, the number can be increased by several orders of magnitude. In the subcritical field at low frequencies, Schwinger mechanism dominates pair creation, and the production is very low. After modulation, the frequency spectrum widens. The high frequency component enhances the multiphoton processes and the dynamical assisted mechanism, while the ultrahigh frequency component inhibits pair creation.