针对利用天基单视线测量信息确定空间目标轨道问题，定义了一种新的可观性指标，分析了高阶摄动项对系统可观性的影响，并给出了单视线测量轨道确定算法。首先，采用李导数推导了系统可观性矩阵，根据系统局部弱可观条件得到了可观性指标，并推导了高阶摄动项可观性的近似计算公式。然后，在近圆轨道假设下建立了空间目标和观测平台轨道参数与可观性指标间的关系。之后，提出了适用于单视线测量的迭代最小二乘轨道确定算法，并推导了轨道确定误差协方差矩阵。数字仿真结果表明：空间目标和观测平台的轨道倾角差是影响系统可观性的主要因素，高阶摄动项通过增加矢量异面度来提高系统可观性；观测平台远离其升交点可保证系统可观性；可观性指标越大，目标轨道确定精度越高；位置估计误差标准差受系统可观性和观测时长影响。

To address the issue of the orbit determination of space targets when using space-based single line-of-sight meas-urement information a new observability index was established. The influence of higher-order perturbation terms on system observability and a single line-of-sight measurement orbit determination method were studied. Firstly, the sys-tem observability matrix was derived using the Lie derivative, the system observability index was obtained based on the locally weakly observable condition of the system, and the approximate formula for the observability of higher-order perturbation terms was derived. Secondly, under the assumption of a near-circular orbit, the relationship be-tween the orbit parameters of the space target and observation platform and the observability index was established, providing a basis for the design of the observation platform orbit. Thirdly, an iterative least squares orbit determination algorithm was proposed, and the orbit determination error covariance matrix was derived. The digital simulation re-sults indicated that the higher-order perturbation term improves the observability of the system by increasing the vec-tor heterohedrality, keeping the observation platform away from its ascending node ensures observability of the sys-tem, a large observability index causes high orbit determination accuracy, and the standard deviation of position esti-mation error is greatly affected by the observability of the system and the observation duration.