The fractal theory developed by the French scientist Mandelbort in 1970s is beneficial in many areas. It greatly expands and deepens our knowledge on irregular geometric bodies. Fractal theory quantifies these phenomena mainly by ascertaining their fractal dimensions. Box counting algorithm is the one most practical and also most frequently adopted method. The traditional box counting algorithm is based on the grid document and has some serious shortcomings

such as the distortion of the image being enlarged

the trivialness of the process and the finite of the iterative degree

etc. The vector box counting algorithm developed in this paper takes vector document as the carrier and has three advantages. First

the image will not be distorted after being enlarged. Second

the process is completely handled by computer

simple and reliable. Third

to some degree

the iterative degree can be infinite. Therefore

it can ascertain precisely the scaling space of the graph and acquire accurate fractional dimension value. This paper expounds the data structures

the process of disposing and the main functions in detail. Whats more

it proves the precision and advantages of the vector box counting algorithm by making use of Koch curve

osteoma boundary and river system. The result shows that the vector box counting algorithm is a convenient

useful and precise way of dimensional calculating method.