The time and frequency primary standard UTC (NIM) is maintained by the National Institute of Metrology (NIM) in China, and is traceable to the international time scale coordinated universal time ( UTC). With the continuous development of information technology, time stamp service is widely used in justice, health, finance, electronic commerce, intellectual property, etc. According to the Chinese government′s demand for legal metrology in areas such as trade settlement and medical, the time provided by time stamp authority (TSA) should be traced to UTC ( NIM) for domestic unification and international equivalence. This article proposes a calibrator to remotely and locally evaluate the traceability of TSA to UTC (NIM). When local calibration is implemented on the LAN, the uncertainties (k = 2) of the time offsets between UTC (NIM) and TSA are generally less than 2 ms. The uncertainties (k = 2) of the time offsets between UTC (NIM) and TSA located in Beijing are generally less than 713 ms on the WAN environment, even if the distance between the calibrator and TSA exceeds 1 000 km.