中文摘要：

本文研究一类平面微分系统，通过作两个适当的变换以及焦点量的仔细计算，得出了该系统的无穷远点与5个初等奇点（-1/2，0），（-1/2，±√3/2），（±1/2，-√3/6）能够同时成为6个广义中心的条件，进一步得出在一定条件下该系统能够分支出12个极限环的结论，其中2个大振幅极限环来自无穷远点，10个小振幅极限环来自5个初等焦点．我们的工作是有意义的，相似的结论在已经出版的文献中少见．

英文摘要：

This paper is concerned with a class of planar differential system of nine de- grees.By making two appropriate transformations of system and calculating focal values care- （-？,0）,（-？, ±√3/2） fully, we obtain the conditions that the infinity and five elementary foci（-？,0）（-？,√3/2± become six general centers at the same time.Moreover 12 limit cycles including 10 small limit cycles from five elementary loci and 2 large limit cycles from the infinity can occur at the same step of disturbance under a certain condition.What is worth mentioning is that similar conclusions have hardly been seen in published paper up till now and our work is significative.