A high linearity and ultra-bandwidth sample/hold circuit with bridge shunt-series cascade structure. The sample/hold circuit included three units, such as input buffer, auxiliary switch and SEF switch. The improved auxiliary switch module unit with bridge shunt -series cascade structure greatly improved the linearity and bandwidth of the circuit. The sample/hold circuit was designed in a 0.13 μm SiGe bipolar process, and it was powered by -4.75 V and 2 V dual supply voltage. The simulation results showed that SFDR was 69.60 dB, THD was -65.25 dB, and -3 dB bandwidth was 35.43 GHz under the conditions of 100 fF sampling capacitance, 6.25 GHz sampling frequency and 10.28 GHz input frequency.