Abstract: Fractal theory has been one of the most important tools for studying coastline character. Fractal interpolation, as a new method to deal with such problems, may create prospective scene image based on a few data of the characteristics of the scene. The fractal interpolation functions are introduced briefly that can deduce the fractal simulation image and the fractal dimension and length of scene curve. On the basis of the above discussion, the fractal interpolation calculation system is developed by selecting Visual Basic as development environment and SuperMap Objects as ActiveX. And taking Tianjin coastline as an example, we use the system to establish fractal simulation image of the coastline, to calculate fractal dimension of the coastline and length of the coastline. The results show that the fractal simulation image, fractal dimension and length of the coastline can be obtained at one fling by applying fraetal interpolation function.