Abstract: Fine roots (roots ≤2 mm in diameter) are the primary organ of absorbing water and nutrients in forest systems. Since the initiation of the large-scale ecological rehabilitation project (known as "Grain for Green" project) by the Chinese central government in 1999, the acreage of the jujube orchard has been increased rapidly on the Loess Plateau mainly for conserving soil plus water and raising economic benefits. However, the knowledge of fine roots dynamics during stand development is lacked to guide management practices for rain-fed jujube plantations, and most studies focused on the vertical dynamic of fine roots, with the method of random sampling and missed characterizing the radial distribution of fine roots. The objective of this study was to investigate the characteristics of fine roots in a rain-fed jujube plantation (Ziziphus jujube Mill. cv. Lizao) with a range of stand ages (2, 6, 10, and 15 years) in Qingjian County in Shaanxi Province (37°15′N, 118°18′E). Specifically, the fine root length density (FRLD), and the specific root length (SRL) in different age classes of a rain-fed jujube plantation at different radial distances were characterized. The distribution of the jujube trees was relatively uniform in 2 m between rows with the distance of 3 m between plants in each row, and the fine root samples were collected at 0.2 m increments to a depth of 3 m in trisection radiation from the representative tree trunk (0, 120, and 240°) at 0.5 m, 1 m, and 1.5 m radial distance in October 2014. The soil samples were collected with a root auger, which included a long cylindrical steel auger with an internal diameter of 0.09 m. The results showed that the fine root length density increased with the stand age increasing, and the surface soil had the highest fine root length density values in the 0-0.6 m surface soil layer, representing 60%-90% of the total fine root length density (from 0 to 3 m) in all study sites. The fine roots of the 2-year-old jujube plantation were distributed mainly in a range of 1.5 m, horizontally, within a thickness of 1.6 m, vertically; while those the 10 and 15-year-old jujube trees have exceeded 1.5 m in the radial direction and 3 m in the vertical direction, and a high-density region of fine roots were observed in the middle of the inter-row in 10, and 15-year-old jujube trees. This suggested that through ten years of fine root system development in the dense rain-fed jujube plantation, the fine roots were overlapped between neighboring jujube trees, and there was no difference of fine root length density in the radical distribution in the mature jujube trees (10 and 15 years, p＞0.05). Stand age had a significant effect on the specific root length (p＜0.05), and the average values of the specific root length were 6.08 m/g, 4.80 m/g, 4.50 m/g, and 3.80 m/g in 2, 6, 10, and 15-year-old jujube trees, respectively. This implied that the younger stands (2 and 6 years) had relatively "thinner" fine roots compared with the mature stands in the rain-fed jujube plantation, which likely occurred because young stands could take advantage of scarce moisture and nutrients. Our results quantified the extent and magnitude of fine root distribution in the soil layers during a chronosequence, which may reflect an increase in the concentration of fertilizer in these soil layers. The outcomes suggest that fertilizer can be placed closing to the main trunk in young stands, whereas fertilizer can be more evenly distributed in mature stands, and local farmers should conduct necessary measurement strategies for soil moisture conservation in the rain-fed jujube plantation.