A flame retarding polymer electrolyte composition containing maleimides includes a modified maleimide; a lithium salt; and at least one ionic solution in a ratio of at least 2 wt % relative to the total weight of the composition. By using the hyperbranched dendrimer-like structure of the modified maleimide as grafted skeleton for polymer electrolytes, the electrolyte composition can encapsulate an electrolytic solution continuously, thus preventing the exudation of the electrolytic solution and increasing the stability of lithium ionic conduction. Since the ionic solution is nonflammable, the safety of batteries are further enhanced when the polymer electrolyte composition is used as polymer electrolyte for a lithium secondary battery.