Abstract: To deeply study the reservoir formation and occurrence characteristics of hydrates, establish geological models for studying the seismic response characteristics of hydrates and free gas reservoirs, and further provide a theoretical guidance for hydrate exploration and identification, hydrates and free gas reservoirs were simulated based on random medium theory. First, according to the actual occurrence status and characteristics of hydrates and free gas in the formation, the contour templates of the occurrence area for hydrate and free gas were established. Secondly, two types of reservoir random medium models were established based on the random medium theory. Finally, based on the contour templates of the occurrence area, the established random medium model was used to achieve numerical simulation of velocity of hydrate areas and free gas areas in the reservoir, and the velocity models for hydrate reservoir and free gas reservoir were established. To approach more closely to the actual geological environment where hydrates are located, uniform velocity formations were individually set up above the hydrate reservoir and below the free gas reservoir, and undulating stratigraphic interfaces were constructed, thus establishing a velocity model for four layer medium undulating interfaces. Compared with actual formations rich in hydrate, the model reflected the complex non-uniformity of hydrate and free gas distribution in hydrate reservoirs, and better simulated the large-scale hydrate and free gas storage areas in formations rich in hydrate.