The present invention discloses mordenite having diatomite morphology and a multi-level pore channel structure, and a preparation method thereof. According to the present invention, cheap diatomite having an unique macroporous structure is adopted as a zeolite preparation template and a silicon/aluminum source, and during the preparation process, a diatomite-porous carbon intermediate is prepared, and then porous carbon is adopted as a template and diatomite is adopted as a silicon source and an aluminum source to prepare the porous mordenite having the diatomite morphology and the large/micro pores. According to the present invention, the obtained mordenite has the diatomite morphology and further has the high macroporosity so as to provide the multi-level pore channel structure, such that the efficient adsorption is provided; and compared with the mordenite processes through other template methods, the method of the present invention has characteristics of simple process and low potential environment hazard.