Large scale of combustible ice was developed in the continent slope area of the western coast of Ecuador. The seismic reflection characteristics are extremely similar to bottom simulating reflection（BSR）. This area belongs to typical deep rugged sea bed, of which the free surface multiples, interbed multiples and diffracted multiples exist in the marine seismic data. Strong energy multiples can decrease the S/N ratio of data, and can affect the accurate imaging of primary reflection, even can severely influence the identification of combustible ice. The cascade combination of free surface multiple attenuation technique, high resolution Radon transform multiple attenuation technique and diffracted multiple attenuation technique were adopted to successfully solve the multiple attenuation problem in this area, which improves the ability of using seismic data to identify the combustible ice and can be used to predict the distribution scale of combustible ice in this area.