Non-classical computation slicing is an abstraction mechanism for pruning state space and it plays an important role in tackling state explosion problem in predicate detection. This paper shows that the slicing technique based on prime event structures can improve the expressiveness of that abstract method and extend its application scope greatly. We introduce the slicing idea into the area of event structure and develop a complete theory framework with related techniques for event structure slicing. This slicing technique can serve as a useful supplement and high level extension to the existent computation slicing which can not handle the situations with conflicts or execution choices.