Abstract: The contents of free and hydrolyzed amino acids in jujube fruits were determined by ultra-high performance liquid chromatography (UPLC) with 253 samples of crisp ripening stage fruits from the National Jujube Germplasm Nursery as the research object. Subsequently, correlation analysis, principal component analysis, comprehensive scoring, and cluster analysis were performed to systematically characterize the variations in 17 amino acids indices across different jujube cultivars. The results showed that: (1) A total of 17 amino acids were identified in all samples, including 7 essential amino acids (hydrolyzed fraction: 19.86-222.80 mg/100 g; free fraction: 0.99-43.79 mg/100 g) and 10 non-essential amino acids (hydrolyzed fraction: 41.85-814.58 mg/100 g; free fraction: 39.15-402.00 mg/100 g). Proline had the highest content, which was 2.6-54.8 times that of each of the other amino acids. Among hydrolyzed amino acids, 11 amino acids (histidine, arginine, glycine, aspartic acid, threonine, cysteine, tyrosine, methionine, valine, isoleucine, and phenylalanine) showed a normal distribution across different germplasms. For free amino acids, 7 amino acids (serine, arginine, glycine, aspartic acid, alanine, lysine, and leucine) also presented a normal distribution among different germplasms. (2) The content of medicinal amino acids in hydrolyzed amino acids ranged from 25.34-496.24 mg/100 g, with aspartic being the most abundant component. (3) The content of medicinal amino acids in free amino acids varied from 3.96-45.98 mg/100 g, and arginine was the most abundant one. In terms of taste-active amino acids, their contents were ranked in the descending order as follows: sweet-type > bitter-type > umami-type > aromatic-type. (4) Correlation analysis results showed that there were correlations among different amino acid components in jujube fruits, and a highly significant positive correlation (P<0.01) was found between most pairs of amino acids. (5) Based on principal component analysis and comprehensive scoring: four principal components were extracted from hydrolyzed amino acids, with a cumulative contribution rate of 81.742%; the top 10 high-quality germplasms with the highest comprehensive scores were Heyang Linglingzao, Tianjin Damayazao, Yuci Tuanzao, Ziziphus jujuba var. spinosa (Suanzao) 2, Suanzao 4, Lejin No. 4, Baode Youzao, Liaocheng Yuanlingzao, Linxian Dasuanzao and Taigu Shenglizao. Five principal components were extracted from free amino acids, with a cumulative contribution rate of 67.622%; the top 10 high-quality germplasms in terms of comprehensive scores were Suanzao 4, Suanzao 1, Xinjiang Xiaoyuanzao, Suanzao 10, Linyi Lizao, Zhongyang Muzao, Qianling Dazao, Hami Dazao, Yongji Hamazao and Ershijia Dazao. (6) The K-means clustering algorithm was used to classify 253 jujube germplasms into three groups with significant differences. The results of this study can provide a basis for the breeding of jujube germplasms with an optimal amino acid composition and the deep processing of such germplasms.