The invention provides a full-MOS voltage and temperature monitoring method and monitoring circuit. The circuit comprises two annular oscillators RO1 and RO2, two time-digital converters TDC1 and TDC2, a temperature mapping module, a voltage mapping module, a reference clock frequency divider module and two compensation modules, wherein a reference block is provided by a crystal oscillator, poweris supplied to the annular oscillator RO1 through a core-domain power supply voltage VDD_CORE, power is supplied to the annular oscillator RO2 through a battery voltage VBAT, the reference clock is separately connected to the TDC1 and the TDC2 through the frequency divider, and output terminals of the TDC1 and the TDC2 are respectively connected to the temperature mapping module and the voltage mapping module. According to the method and circuit, real full MOS can be realized, extra masks are avoided, effective calibration of the PVT is realized, the monitoring precision is improved, and the method and the circuit are advantageous in that the structure is simple, the area is small, and static power consumption is avoided.