In fact, the sea wave is considered as a stochastic process. The random characteristics of the sea wave are described by a suitable spectrum. Offshore structures analyzing on random concept may be determined by creating a random wave surface from a defined wave spectrum for the sea area of consideration. This paper presents the method to establish random wave surface in Vietnam’s sea areas based on any suitable wave spectrum. Hereby, hydro -dynamical characteristics of waves can be determined for further calculation of wave loads on offshore structures. | Establish random wave surface by a suitable spectrum in the Vietnam s sea