In order to improve the positioning accuracy and guiding accuracy of an airborne measuring device, a mathematical model of error analysis is established based on the coordinate conversion equation from geodetic coordinates to telescope coordinates deduced by the homogeneous coordinate conversion theory. The effects of some parameters in airborne measuring device on positioning result and guiding result are theoretically analyzed using Monte-Calro method. Several approaches to improve the accuracy of airborne measuring device are presented, such as improving the attitude accuracy and position accuracy of airplane. In addition, it is pointed that data processing is also an effective method to improve the positioning accuracy. The results indicate that positioning accuracy and guiding accuracy can both be increased by 30% through changing airplane attitude accuracy from 0.3°to 0.1°, and positioning accuracy can be enhanced by 9% through changing airplane position accuracy from 20 m to 5 m. The analysis process and result are useful for designing airborne measuring device.