According to the data of air temperature for nearly 40 years(1961—1999) at 20 weather stations around open trench of desert in hydraulic engineering of diverting water of Erqisi river into Urumqi and other data (longgitude,latitude and height above sea level), and applying ways of climatology,geography,hydraulic engineering and entropy meteorology, models of mean air temperature (April and July) , annual mean air temperature and stable period of water transmission in the open trench of 170km are built, meanwhile, by means of probability models of normal distribution , design value are obtained, so the distribution laws of these circumstances are disclosed.