Base on the ZigBee technology, a wireless sensor networks for remote home environment monitoring and health care monitoring was built in this paper, and the applications of data fusion algorithms in system of front & back end data processing were deeply discussed. The experiment is proved that the applications of data fusion algorithm, which is a combination of Bayesian estimation and fuzzy reasoning, could effectively reduced the network information redundancy and Internet delay of wireless sensor networks. It is also improved the accuracy and reliability of data and the network lifetime of this system.