The invention discloses high-selectivity shallow-groove-isolated chemical-mechanical polishing slurry. The slurry is prepared from water, cerium oxide, dispersants, salts of poly(methacrylic acid) and pH buffer regulators; by mass, the content of the cerium oxide is 0.3-25%, the salts of poly(methacrylic acid) are 0.05-5% of the solid cerium oxide, the dispersants are 10-50% of the salts of poly(methacrylic acid), and the content of the pH buffer regulators is 4-6%. The invention further discloses a preparation process of the high-selectivity shallow-groove-isolated chemical-mechanical polishing slurry. Through the adoption of the preparation process, the obtained CMP cerium oxide polishing slurry has the advantages of being high in selectivity and cutting velocity, good in abrasion resistance, concentrated in particles, not agglomerated and the like, and is suitable for industrial production and control.