Map projections are attempts to portray the surface of the earth or a portion of the earth onto a flat map surface. This can
not be done without any distortions of conformality, distance, direction, scale, and area. There are many map projections,
and each of them has its own set of advantages and disadvantages. The mapmaker must select the one best suited to their
application needs, reducing distortion of the most important features. However, how to select a 'proper' map projection
is a complex process involving general evaluation of map projection alternatives based on a set of characteristics that
describe these projections. And this process needs a systemic understanding of map projection, which usually can not be
achieved by end users. This paper introduced Expert system (ES) to solve this problem, and used Component Objects
Model (COM) technology to develop and interoperate the proposed system (developed with Visual Prolog 7.0 Personal
Edition®) with professional Geographical Information System (GIS) software. As an essential part of the article, the
authors also represented the knowledge, rules and reasoning methods of selecting an appropriate map projection as well.
Implementations and examples had been given to testify the feasibility.