Abstract: Symbolic-numerical computation is a novel method of solving large scale problems，which applies both numerical and symbolic methods in its algorithms and provides a new perspective of them.The theoretical research has already obtained much progress while at the same time the designing of symbolic-numerical computation system still lies in discussion.A novel method is used to design such systems based on the free SYNAPS library，and then the hybrid computation system is implemented.Experimental results show that the system presented here is efficient and reliable.

Key words: Computer Algebra System（CAS）, symbolic-numerical computation, mathematic software, symbolic and numeric applications（SYNAPS）

摘要： 符号与数值混合计算是一种利用数值计算和符号计算方法解决大规模问题的计算方法，它为符号计算与数值计算提供一种新的思维模式和方法。近年来，混合计算的理论研究取得一些重要的进展。然而，混合计算的系统软件设计还处于探索阶段。基于此，提出了一种基于改进的开放源代码的符号数值计算应用环境库（SYNAPS）的高效符号数值混合计算系统的设计方法，并进行了实现。实验结果表明，该系统高效可靠。

关键词: 计算机代数系统, 符号与数值混合计算, 数学软件, 符号与数值混合应用