捷联惯性导航系统/天文导航系统/全球导航卫星系统（SINS/CNS/GNSS）构成的组合导航系统可有效提高飞行器的定位精度，而导弹等飞行器常用发射时刻的发射点惯性坐标系作为测量载体飞行的基准。为此，首先在发射惯性坐标系下推导并建立一种简洁的SINS/CNS/GNSS组合导航数学模型，该模型将SINS积分预报姿态四元数误差作为待估量，可避免姿态误差角与数学平台失准角之间的转换；然后分析定位误差导致的引力误差量级并合理简化，推导符合实际的精确测量噪声模型；最后利用扩展卡尔曼滤波器（EKF）实现SINS/CNS/GNSS三种信息的有效融合。算法仿真结果表明该方法的有效性，有利于工程实现。

The integrated navigation system composed of strapdown inertial navigation system/celestial navigation system/global navigation satellite system(SINS/CNS/GNSS) can effectively improve the positioning accuracy of missile and other aircraft, which often use the launch point inertial coordinate system of launch time as the datum. Firstly, we deduce and establish a simple integrated navigation mathematical model of SINS/CNS/GNSS under the launch inertial coordinate system, and take the attitude quaternion error of the model as an estimation to avoid the conversion between the attitude error angle and the misalignment angle of the mathematical platform. Then, we analyze and reasonably simplify the magnitude of gravity error caused by positioning error, and an accurate measurement noise model is derived. Finally, we realize the effective integration of SINS/CNS/GNSS by using extended Kalman filter(EKF). Simulation results show that the proposed method is effective and beneficial to engineering implementation.