To create an efficient monitor with limited complexity and less cost at runtime from top-level specification is very important in research on runtime verification. By deleting and merging most status of Büchi automaton, a new way was proposed to construct an efficient anticipatory monitor which was based on the anticipatory semantics of Linear Temporal Logic (LTL). Through this method, on one hand, much smaller final anticipatory monitor was generated and the efficiency was improved that of the generation of the monitor; On the other hand, the runtime cost of the monitor was control into a reasonable region. A tool named ” monitor_tool” was implemented to check the approach above, it’s more effective than LTL3_tool and able to generate monitors for more LTL properties.Meanwhile,The generated monitor can identify a continuously monitored trace as either satisfying or falsifying a property as early as possible.