From the angle of practical application,this paper comes up with the numeral system conversion taking decimal as center based on the principle of numeral system conversion algorithm.The mainly is the conversion among binary,octal,decimal and hexadecimal.Making use of MFC and this algorithm,the converter among binarye,octal,decimal and hexadecimal is implemented.In this process,the algorithm of acquiring weight is proposed.The algorithm of this paper is logical and it is simple to implement.