The composition control of hyperdispersants is crucial for their dispersionproperty of nanoparticles. In this paper，a comb shaped copolymer P（AA-co-MPEGAA）was prepared using acrylic acid（AA）and methoxy polyethylene glycol acrylate（MPEGAA）as raw materials. The competitive polymerization rate of the two monomers was measured by high-performance liquid chromatography（HPLC）combined with composition analysis，the uniform control of copolymer composition was achieved. And the effects of copolymer composition andcomposition control，pH value，dispersant dosage，and other conditions on the dispersionperformance of nano ceria particles were systematically studied. The results indicate that theperformance of a uniformly composed hyperdispersant is superior to that of a non-uniformcomposition. Under neutral and alkaline conditions，the optimal comprehensive dispersion performance of ceria particles is achieved when the molar fraction of MPEGAA units in thecopolymer chain is 0. 20.