The performance evaluation of wireless sensor network based on passive monitoring restricted by two respects: first, passive monitoring trace is incomplete, because monitors can not capture every transmission in the network. Second, the information directly extracted from trace is insufficient. Performance evaluation always needs some implicit information, e.g., packet reception. To solving the problems above, we use two processing steps to construct an enhanced trace of network. First, an online merging procedure combines the incomplete traces of various monitors into a single more complete trace. Next, an inference procedure based on finite state machine reconstructs packets that were not captured by any monitor and determines whether a packet was received by its destination. Merging and inference procedure are realized in CTP Network which is incorporated with TinyOS. The evaluation is performed on simulation. The experiment results show that, if the trace contains more than 70% of the total packets, the engine can infer 20%-25% more loss packets and 90% packets' reception.