The interactions between a two-level atom and a squeezed field of time-varying frequency have been investigated. The properties of the atomic population inversion for two typical cases——the frequency of the field varying with time in the forms of sine function and rectangular pulses——have been considered. For the frequency changing with time in sinusoidal form, the collapse-revival phenomenon of the atomic population inversion is deformed not only by the frequency-modulation but also by the squeeze coefficient and the squeeze phase of the field. The sudden jumping of the field with rectangular pulsed frequency-modulation can lead to new collapses and revivals in the evolution of the atomic population inversion. The rectangular pulsed frequency-modulation can also lead to small-amplitude fast oscillations of the atomic population inversion during the pulse. There is no relation between the latter phenomena and the squeeze coefficient of the field.