Abstract: The mathematic theories for uncertainty model of line segment are summed up to achieve a general conception, and the line error band model ε σ is a basic uncertainty model that can depict the line accuracy and quality efficiently while the model of ε m and error entropy can be regarded as the supplement of it. The statistical characteristic of the line error is developed deeply by analyzing the probability that the line error falls inside a certain range. Moreover, the theory accordance is achieved in selecting the error buffer for line feature and the error indicator. The relationship between the accuracy of area for a polygon and the error loop for a polygon boundary is deduced and computed.