Based on the theory of error,analysis on several factors which affected the short-range leveling accuracy in the Mime Basin and in-site test were done. The result shows that the accuracy of short-range leveling was mainly affected by four interference factors as follow: (1)error of leveling rod length which was caused by change of temperature; (2)the instrument warmed only on one side; (3)sinking of rod stake F (4)photo-refraction error on ground. It is emphasized that the fourth factor was more disadvantageous than the others. Therefore,some advanced measures against the disadvantageous factors were adopted and abvious effect was obtained, the observed precision was raised from ±0.40 mm/km to ±0.26 mm/km.