The gyrotheodolite is a kind of defining orientation physical instrument,which can measure true north in all-weather and does not depend on other conditions.It has been broadly used in these realms,such as military affairs,launch of long-distance armament,spaceflight,mine,railway,forest,architecture,voyage and mapping.The stability of apparatus constant will directly influence on the stability of the result in the orientation of gyrotheodolite.In this paper,the surveying method of the constant was introduce...