To overcome the limit with high-speed analog to digital convertion (ADC) required for real time sampling of the high-bit-rate optical signal,in t his paper,an all-optical equivalent-time sam pling system based on four-wave mixing (FWM) in highly nonlinear fiber (HNLF) is set up.The all-optical sampling system mainly consists of the sampling optical pulse signal unit, all-optical sampling gate unit and signal processing unit,where the all-optica l sampling gate is the core of the sampling system which can complete the all-o ptical sampling of high-speed optical signal.The all-optical sampling is imple mented based on four-wave mixing effect when the sampling pulse a nd the signal are injected into the highly nonlinear optical fiber.In order to v erify the feasibility of the sampling system,10Gbit/s and 40Gbit/s not-retu rn-to-zero (NRZ) on-off keying (OOK) signals are used for the sampling experi ments.Experimental results show that the sampling system can achieve high-speed optical signal sampling procedure.At the same time,the sampling system is simpl e,not subject to the limitations of the optical signal rate,and can be applied t o higher-rate signal measurement.