Some physicochemical characteristics of calamondin (Citrus microcarpa) from Hainan were determined in this study. The mean length, width, and thickness of calamondin were (2.763±0.262), (2.721±0.189), and (2.684±0.201) cm, respectively. The average values for geometric mean diameter, sphericity, fruit shape index, mass, surface area, volume, true density, bulk density and porosity were (2.721±0.196) cm, (98.79±5.149)%, (101.64±7.609)%, (11.18±2.149) g, (23.36±3.362) cm2, (11.16±2.115) cm3, (1.00±0.060) g/cm3, 0.44 g/cm3, and (56.40±0.027)%, respectively. The mean edible part, juice rate, and soluble solids were (85.77±3.53), (48.36±4.20), and (7.86±0.09)%, respectively. The total flavonoids, pectin, limonin, reducing sugar and volatile oil contents of the peel were 1.00, 7.14, 0.51, 5.98, and 4.25%, respectively. The total flavonoids, pectin, limonin and reducing sugar contents of the pulp were 0.02, 5.04, 0.03 and 4.56%, respectively. The total flavonoids, total acid, reducing sugar and vitamin E contents of the juice were 0.11, 6.74, 0.37%, and 1.68 mg/kg, respectively, while the content of vitamins A, B1, B2, B3, B6, and D in the juice was very low. The seeds had limonin, reducing sugar and oil contents of 0.46, 1.39, and 30.46%, respectively. The vitamin B2, B3, B6 and E contents of the fruit residue were 44.83, 19.31, 17.55, and 15.72 mg/kg, respectively. The amino acid profile of the residue included aspartic acid, glutamate, cystine, serine, glycine, histidine, arginine, threonine, alanine, proline, tyrosine, valine, methionine, isoleucine, leucine, phenylalanine and lysine, with respective contents of 4.42, 1.81, 2.10, 0.78, 0.59, 0.20, 0.72, 0.16 0.67, 3.65 0.50, 0.67 0.59, 1.00, 0.76, 0.57 and 0.91 g/kg.