Wireless Sensor Networks (WSN) have been widely used in various monitoring applications including virtual fencing. With the integration of Internet of Things (IoT) in which millions of devices, systems and services will be interconnected online, it brings high capabilities for sensing, intercommunicate and actuation. This paper presents the experiments and performance analysis of virtual fence unit consists of microwave motion detector and IEEE 802.15.4 WSN for maximum sensing range integrate with IoT. In particular, the analysis is focusing on the maximum sensing range in terms of azimuth angle, height, sensitivity level for indoor and outdoor implementation. With the help of IoT, sensor which detected motion on weak detection angle or signal could communicate through internet and get signal from nearby sensor for better detection signal. The WSN platform is developed using Octopus II sensor nodes while the microwave motion detector is HB100 which detect movement using Doppler effects. Octopus II will uplink all signal through internet and provide corresponding action of virtual fencing when intrusion detected. Results show maximum sensing range of virtual fence unit is decreasing as azimuth angle increasing. With high sensitivity level of virtual fence unit, the maximum sensing range of virtual fence unit is larger than the maximum sensing range of virtual fence unit at normal sensitivity level. Results also show the virtual fence unit has higher maximum sensing range in indoor environment than outdoor environment.