针对星光折射法间接敏感地平星敏感器视场内折射星数量不足的工程问题，对折射星数在星敏感器视场内的概率分布进行了研究。阐述了星光折射间接敏感地平的基本原理；推导了视场内平流层条带面积占视场面积的比例系数，并在视场内可观测星数概率分布模型基础上，得到了折射星数的概率分布模型。对星光折射解析定位新方法进行了可行性分析，给出了星敏感器视场、极限观测星等、轨道远地点距离与视场内折射星数分布之间的关系。折射星数概率分布曲线与用蒙特卡罗方法获得的概率分布曲线相似，泊松参数偏差为1.48，相对误差为12.8%。仿真结果表明了该模型的正确性和有效性，该模型对于间接敏感地平星敏感器参数设计具有指导作用。

Aiming at the engineering problem that the refracted star number in the field of view (FOV) of a star sensor is not enough to carry out indirectly sensing horizon, it is necessary to study the probability distribution function (PDF) of refracted star number in the FOV. A brief introduction of the principle of stellar refraction is given. The proportion coefficient of the stratosphere strip area fallen in the FOV to the whole FOV area is deduced, and combined with the validated PDF of the total star number in FOV, the PDF of the refracted star number is obtained at last. The feasibility analysis on the analytic positioning method based on stellar refraction is finished by using the PDF model, presenting the quantification relationship between the FOV, apparent magnitude (Mv), apogee distance and probability distribution. The plotted refracted star number PDF curve is similar to that by Monte Carlo simulation results, with Poisson parameter bias of 1.48, an equivalent of relative error of 12.8%. The simulation results show the correctness of the PDF model, which will be helpful to the parameter design of the star sensor used for indirectly sensing horizon through starlight refraction.