Localization and reconstruction of the human motion trajectory based on high density and low cost PIR sensor is an important direction for the behavior analysis of people.The walking of persons can be detected through the 0-1 response of the PIR sensors.The identification and tracking of the behavior of the crowd can be achieved through the different sensor response sequence of spatio-temporal sequence relationship.Most of the existing analysis methods for PIR sensor network have revealed the statistical characteristics of crowd movement from the perspective of group behavior

but there still exists many problems in the estimation accuracy and uncertainty of behavior.Arming at the reconstruction of personal behavior trajectory in PIR sensor network

the geometric algebra is introduced to achieve the united expression of topological network of PIR sensor

spatial and temporal response of data sequence and the behavior of the person

thus judging the network connectivity according to the response of spatial and temporal relations of the sensors.Based on the geometric algebra operators

the extension and expansion rules of the trajectory are constructed

and behavioral trajectory reconstruction algorithm is constructed with the PIR sensor network response sequence data.Finally

the rationality and effectiveness of the method are demonstrated by using the continuous observation data of MERL laboratory.