The affected factors for an accuracy of theodolite system are not only the measurement environment of temperature, illumination, etc. but also the measurement processes of the distance between two theodolites, the distance from theodolite system to scale bar and the distance from theodolite system to targets. We have known that the best collimation distance between two theodolites and the best distance from theodolite system to scale bar is $3{sim}4m$. This study was performed for searching the best distance from theodolite system to targets on above measurement configuration. And, we could know that the best distance from theodolite system to targets is $2{sim}6m$ and the system accuracy could be within ${pm}0.025mm$.