This paper analyzes the causes of prism constants and introduces the process of determinating prism constants on construction sites by the stepped method as well as the result,which meets the requirements in construction.

On the bases of the conception of prism constants,this paper introduces the survey errors caused by uncorrected prism constants of total station in different cases according to analyzing one typical survey model,and expatiates the errors which would affect the course of cadastre survey work by enumerating an example.

this paper explains facility method to measure prism constant based on practice experience in surveying and mapping work.