In TSV (through-silicon-via) 3D-ICs, stacking multiple dies faces a severe challenge of the thermal effect due to the low thermal conductivity of inter-layer dielectrics and high power density. In this paper, a thermal control mechanism with an in-situ temperature sensor for TSV 3D-ICs is proposed using thermal guard rings and thermal TSVs. Depending on the thermal guard ring and thermal TSVs, an analytical model for on-chip heat dissipation in each power-thermal domain is also presented in this paper. Based on the analytical model, the offset temperatures between the hotspots in the power-thermal domain and thermal guard ring can be calculated. Therefore, the in-situ temperature sensor is placed near the thermal guard ring to detect the temperature and feedback the thermal information for the system. The simulation results show the thermal control mechanism with an in-situ temperature sensor can reduce temperature and detect heat dissipation of TSV 3D-ICs significantly. This technique can be extended to balance workloads in the overall system for further reducing temperature.