A calcium citrate salt and its preparation method and application are disclosed. The calcium citrate salt has stronger nutritional and therapeutical effects than simple calcium citrate. The preparation method comprises the following steps: dissolving citric acid in water, adding calcium oxide or calcium hydrate or calcium carbonate, filtering to remove foreign materials after the solution is dissolved to be transparent, adding L-arginine or L-lysine or acetyl L-carnitine or propionyl l-carnitine into a filtrate, reacting at 0-100 DEG C for 2-8 h, carrying out vacuum concentration, cooling, carrying out crystallization by adding anhydrous ethanol, filtering and drying, and detecting to be qualified so as to obtain the product. A composition containing the calcium citrate salt can be made into one or more pharmacologically acceptable excipients, especially a solid-liquid oral preparation, such as pulvis, a particulate agent, a tablet, capsules and an oral liquid, etc., or directly made into a beverage, and can be used as dietary / nutritional supplement for human or a feed supplement for animals, including nutritional supplements for supplementing L-arginine, L-lysine, acetyl L-carnitine and propionyl L-carnitine.