Abstract: The problem of forward and inversion of location methods with sun shadow are studied in this paper Based on the change of shadow length, by using spherical triangle function, a relational model between shadow length with data, time, longitude, latitude and solar zenith angle is established And then using this expression to carry out inversion, specific time and testing place can be got by the shadow length change In the time and space location, two different methods are compared by using the matching search and the least square, respectively Finally, the error analysis and correction based on the atmospheric refraction are isproposed.