A sense-amplifier circuit of a memory, which includes a sense-amplifier unit, a first switch unit and a second switch unit. The sense-amplifier unit is constituted by a plurality of transistor switches and having a first, a second, a third and a fourth connection terminal. The first switch unit is configured to be parallel coupled between the first and second connection terminals of the sense-amplifier unit. The second switch unit is configured to be parallel coupled between the third and fourth connection terminals of the sense-amplifier unit. The first and second switch units each are constituted by a plurality of transistor switches coupled in parallel and are configured to control each of the parallel-coupled transistor switches on or off in the first and second switch units so as to calibrate a sensing range of the sense-amplifier unit. A calibrating method for a sense-amplifier circuit of a memory is also provided.