Abstract: This is an essay in the field of process mineralogy. Deep sea rare earths are the fourth deep-sea mineral resource after polymetallic nodules, cobalt rich crusts and polymetallic sulphides. Taking the mud grade components of deep-sea sediments in the Western Pacific as the research object, this paper finds out that the sediment type of the sample is medium-grade deep-sea clay sediment, and the main elements in the mud grade samples are Al, Si, Fe, Mn, Na, Mg, K, etc, The main mineral phases are amorphous quartz, feldspar, clay minerals (illite (11.4%), montmorillonite (16%), clinoptilolite (20%) and calcium cruciform zeolite. The M/I ratio of the sample is 1.40, suggesting that it may be affected by volcanic materials. The mud fraction is mostly composed of aggregate particles formed by clay minerals and amorphous quartz. The fine apatite particles are embedded in the aggregate in a star shape, and REY may be mainly enriched in apatite particles.