The invention discloses a modulator capable of reducing the influence of high-frequency noise in a fractional frequency synthesizer, and a modulator circuit. The modulator circuit comprises a gear selection module, a multi-stage cascade modulation module and a notch filtering module, wherein the gear selecting module is used for selecting a decimal intercepting digit and a corresponding notch filtering circuit; the notch filtering module is used for carrying out partial interception before an input decimal value enters the multi-stage cascade modulation module, restoring the value to an original expected value through the notch filtering circuit after processing by the multi-stage cascade modulation module, and reducing the noise spectral density at the high frequency. According to the modulator capable of reducing the influence of the high-frequency noise in the fractional frequency synthesizer, and the modulator circuit, through the modulator and the configurable notch filtering structure of the circuit thereof, the frequency of the output high value can be reduced, and the additional filtering effect on the high-frequency noise is achieved.