Based on a 65 nm CMOS process, a subthreshold MOSFET voltage reference with second-order temperature compensation was designed. The reference generator utilized gate-source voltage difference for CTAT voltage between two NMOS transistors, which both operated in subthreshold region to achieve second-order temperature characteristics. The second-order temperature characteristics of CTAT voltage was opposite to the second-order temperature characteristics of PTAT voltage. By using current mirror technology, the gate-source voltage difference that was complementary to absolute temperature was added to the output of the voltage reference. Simulation results showed that a temperature coefficient of 5.9 ×10-6/℃ at 1.2 V was achieved from -55 ℃ to 160 ℃. The reference generator operated under supply voltage ranging from 1.1 V to 1.5 V with an output voltage of 273.5 mV and a power consumption of 10 μW.