The present work is a continuation and improvement of the application of the generalized extreme value distribution to study the seismicity of the Southeast Asia. We have applied the generalized extreme value distribution (GEV) method to estimate maximum magnitude value (Mmax) for the earthquake catalog of Northern Vietnam. Using this method, we obtain the distribution of maximum earthquake magnitude values. This distribution can be characterized by its quantile Qq(t) at any desirable statistical level q. The quantile Qq(t) provides a much more stable and robust characteristic than the traditional absolute maximum magnitude Mmax (Mmax can be obtained as the limit of Qq(t) as q ? 1, t ? 8). The parameters have been obtained: ? = - 0.178 ± 0.08 ; ? = 0.23 ± 0.08; ? = 4.39 ± 0.16; Mmax = 6.8 with the probability of 98% for period 2014 - 2064.