针对数字天顶仪，研究一种解算CCD坐标系x轴与北向之间夹角以实现定向的方法。通过对称位置两幅星图解算得到的天顶仪旋转轴的天文坐标，与已知测站点位置真值进行运算，得到相应的切平面坐标系倾斜量。结合双轴倾角仪测量的倾角计算倾角仪X敏感轴的方位角，并运用最小二乘算法解算出倾角仪的定向角，最终解算出CCD坐标系x轴方位角而实现定向。对数字天顶仪的一个工作循环采集的数据进行解算，得到的方位角标准差σ=3.06′，CCD坐标系x轴方位角满足3σ要求，可以实现定向的目的。

Current research on digital zenith camera is mainly focused on the positioning application, so a method of calculating the angle between the x axis and the north direction of the CCD coordinate system is studied.Based on the calculation of the astronomical coordinates of the rotating axis of the zenith telescope obtained from the two stars in the symmetric position, and calculating the true value of the position of the measuring station, the corresponding tangent of the tangent plane coordinate system is obtained.With the angle of 2-axis inclinometer measurement, we calculate the inclinometer X-sensitive axis azimuth angle, and using the least squares algorithm, calculate the directional inclinometer angle.Finally,we calculate the CCD x axis azimuth, directionally.The experimental results show that the digital zenith camera in a work cycle of data calculation, gets the azimuth angle of the standard deviation of  σ=3.06′.Thus CCD x axis azimuth meet the requirements of  3σ, can achieve the purpose of orientation.