In the hydrostatic leveling system (HLS) the working medium is liquid. Because of its merits

water is chosen as the working medium in the HLS. In the HLS system both pressure and temperature have great effects on the surveying results. In this article the influences of pressure and temperature on the HLS are analysed. In order to dispel the influence of pressure on the system

sealing the vessels and connecting the whole system to a common air circuit were adopted as the solution. This circuit was set under ambient atmospheric pressure at a single point of the network. The influence of temperature on HLS includes the temperature gradients existing in the water pipes and thetemperature difference among vessels. After analysis we know that

if we can keep the water level of the pipes as equal as possible when the system is assembled

the influence of the temperature gradient can be eliminated effec- tively. For correcting the effect of temperature variation among vessels

temperature sensors were installed in every vessel to survey the real-time temperatures

and the data were be collected along with the CCD data. And it is through theoretical analysis that we can get the correction formula

by which the errors resulting from the temperature varia- tion can be corrected.