In this paper, the shortcomings in theory and limitation in applications of FOIL are analysed. To overcome these difficulties, instance graph H_(R,E) and instance order are introduced to clarify the relationship between the set R of recursive rules and the instance space E. Based on these concepts, a new ILP algorithm, FOILPlus, is put forward, which prevents the generation of harmful recursive rules by utilizing hung example and hung arc to hold Instance Graph. The algorithm can complete learning tasks without the restriction of constant ordering, and does not substantially raise the computational complexity compared with FOIL. FOILPlus has been implemented, and experiments with it show that it does complete two learning tasks which FOIL fails.