Thrombosis became one of the most severe disease hazard to human health, and it incidence rate grows increasingly higher throughout the world. The conventional diagnosis and monitoring thrombosis mainly relied on the invasive techniques, e.g., digital subtraction angiography and blood sample analysis, and expensive and ionizing techniques, e.g., magnetic resonance angiography. And those techniques can not measure continuously. Here we reported our preliminary exploration of using near-infrared spectroscopy (NIRS) in clinical monitoring of thrombosis. 7 healthy subjects and 6 thrombosis patients at similar age participated the NIRS measurements of oxy- and deoxy- hemoglobin ([HbO2] and [Hb]) on 6 particular parts of legs. We repeated [HbO2] measurement at the same specified time each day after thrombolytic therapy for one single-leg-DVT patient, and terminated till the patient was cured and left hospital. We found that：(1) [HbO2] kept lower in thrombosis patients and [Hb] kept lower in healthy people (p<0.001); (2) [HbO2] kept increasing in the thrombosis leg but decreasing in healthy leg for the patients after thrombolytic therapy, and coincidently, [HbO2] acted consistent just when the patients were cured and left. Our study successfully extended the application of NIRS in noninvasive, continuous, and low-cost monitoring of thrombosis in clinics. Our findings showed the powerful potential of [HbO2] by NIRS in diagnosis and therapeutic effect evaluation of thrombosis.