The invention relates to health care products, in particular to a liquid preparation for calcium supplementation and a preparation method thereof. The liquid preparation for calcium supplementation includes the following components by mass percentage: 3-10% of calcium glycinate, 10-30% of erythritol, 0.1-0.5% of polydextrose, 0.01-0.1% of aspartame, 0.1-0.5% of potassium sorbate, 0.1-1.0% of citric acid, 0.01-0.1% of essence, 1-10% of sodium carboxymethyl cellulose, and the balance water. The invention provides a liquid preparation for calcium supplementation and a preparation method thereof. The content of calcium glycinate effective components can reach 60mg/ml maximumly, so that the liquid preparation is convenient for children and the elderly or patients with dysphagia to take orally, can effectively realize calcium supplementation to children, increases the bone mineral density in the elderly, does not generate calculus in clinical pharmacological experiments, and has stable blood calcium level, good tolerance and no adverse reaction.