The use of ground penetration radar（GPR）for surveying glacial structure and ice thickness is a common method of monitoring glacial variation, but how to extract accurately the information and ice thickness is often more concerned about data interpretation. In this paper, we have run a Finite-Difference Time-Domain (FDTD) model that solves Maxwell′s equations in two dimensions, by comparison simulated image and the results of measured radar, and  analyzed  several reflection characteristics within several profiles, such as crevasses, melting cave, and temperate ice and so on. Comparison results show that GPR reflection image is affected by many factors, such as medium thickness, morphology, roughness and other factors as well in addition to dielectric constant.The survey result also shows that the icebody temperature  at Lao hugou valley No.12 glacier as polar continental glacier presents a higher trend.  Meteorological and historical data indicate that  the retreat and ablation of glaciers have been aggravated   in recent years. Meanwhile, GPR combined  with FDTD simulation provides good analytical tools for monitoring glacial variation along with climate change in our future.