The invention provides a locating device and a machining system. The machining system comprises the locating device. The locating device comprises a base, a lifting mechanism and a jacking mechanism,wherein the lifting mechanism comprises a lifting power part, a lifting driving part and a supporting assembly; the jacking mechanism comprises a jacking power part and rigid padding parts. The lifting power part does reciprocating motion between a rising position and a dropping position relative to the base. The supporting assembly is separated from the base to have a first space when the liftingdriving part is located in the rising position, and the rigid padding parts are driven by the jacking power part to be padded within the first space. According to the locating device and the machining system, the lifting driving part located in the rising position is padded and supported through the rigid padding parts; even if the lifting driving part lifts up a carrier and is integrally supported on the rigid padding parts, the rigid padding parts cannot deform in the pressure direction, the stability of the carrier is guaranteed, and the locating accuracy is improved.