Abstract: The latest underground nuclear test on the 3rd of September 2017 at 11:30 of local time is many times more powerful than the previous tests. This issue was world-shaking, therefore, a Late-Breaking specific session of " North Korean September 3, 2017 Declared Nuclear Test” was proposed to the AGU Fall meeting 2017 in New Orleans by William Walter and Douglas Dreger. The displacement field and stress field generated by this nuclear test had been simulated by some scientists. From the results, the notable effect of this nuclear test on crustal movement observation data in Northeast China is within 110 km. In this paper, we show completely different observation results from groundwater level of two wells which are about 335 km and 420 km away from the nuclear test site in Northeast China, respectively. Both of the two wells have well-confined aquifer systems and are located in the west side of Yalvjiang Fault. The absolute amplitudes of induced well-water level step were observed as 50 mm and 7 mm, respectively. The objectivity of the step-like changes signal was detected and validated after possible disturbances of the well water level had been seriously investigated from atmosphere and precipitation, as well as from local exploitation nearby the wells. Further researches on physical mechanics and their implications are undergoing.