The application provides a sense amplifier and an operation method thereof. The operation method for the sense amplifier includes: during a first phase, initializing a first sensing input voltage and a second input sensing voltage; and recording a first sensing output voltage and a second sensing output voltage of a previous round by charges stored in a plurality of transistors of the sense amplifier; during a second phase, sampling the first sensing output voltage and the second sensing output voltage of a current round as a plurality of transit points; during a first sub-phase of a third phase, amplifying a voltage difference between an input signal and a first reference voltage; and during a second sub-phase of the third phase, pulling the first sensing output voltage and the second sensing output voltage into a full-swing voltage range, and recording charges to the transistors of the sense amplifier.