The invention discloses low sodium polishing solution. The low sodium polishing solution comprises the following raw materials in parts by weight: 20-40 parts of silicon dioxide, 1-5 parts of fatty alcohol polyoxyethylene ether sodium sulfate, 1-6 parts of calcium lactate, 1-10 parts of aluminum hydroxide, 0.5-2.5 parts of diethanol amine, 0.5-2.5 parts of hydroxyquinoline, 10-20 parts of hydroxypropyl methyl cellulose, and 40-60 parts of deionized water. A preparation method for the low sodium polishing solution comprises the following steps: selecting a suitable amount of the fatty alcohol polyoxyethylene ether sodium sulfate, the diethanol amine, the aluminum hydroxide, the hydroxyquinoline and the deionized water according to a weight matching ratio, placing the raw materials in a stirring kettle, and stirring for 5-15 min in a condition of 60-80 DEG C, wherein a stirring speed of the stirring kettle is 100-300 r / min; putting the silicon dioxide, the calcium lactate and the hydroxypropyl methyl cellulose into the stirring kettle, stirring in a warming condition, wherein the stirring speed of the stirring kettle is 600-1200 r / min; and 3) adding a pH value regulator, after filtering, to obtain the polishing solution. The low sodium polishing solution is capable of improving washing efficiency of a wafer, reducing scratching probability, and effectively reducing later period waste liquid treatment cost of the polishing solution, thereby improving the cmp polishing effect.