As a major and strategic national scientific and technological infrastructure element, a high-precision ground-based timing system is an important guarantee to meet the demand for high-precision time and frequency in various important fields. To this end, the differential technology of the eLoran timing system can improve the timing accuracy from a microsecond to less than 100 nanoseconds. To further study the performance of this timing system, this article carried out tests around the Pucheng BPL long-wave station and the Xi’an temporary differential station, corrected the before-differencing signal by using differential correction data, analyzed the mean and variance of the before-differencing signal and the after-differencing signal received at different test points, and verified the accuracy and stability of the timing, providing support for the improvement of the high-precision ground-based timing system. Based on the original study of differential systems, the ASF was divided into two parts, the ASF Spatial term and the ASF Temporal term. The differential correction process and the actual differential correction effect were analyzed by the waveform of the ASF Temporal term. Two conclusions could be drawn from this test validation. On the one hand, differential technology not only improved the timing accuracy, but also ensured the stability of the timing results. On the other hand, the differential timing accuracy improved from 10–20 ns to within 10 ns within 60 km of the differential station. Beyond 60 km, the timing accuracy reached 100 ns, even at a distance of 86 km.