Intelligent building can provide safety, convenience, efficiency and entertainment for life in the 21 century. The most importance role of the intelligent building is security system. In the paper, we focus on the fire detection and intruder detection of the security system, and use intelligent security robot to guard the safety for life and wealth in the intelligent building. We propose an adaptive fusion method for fire detection, and uses smoke sensor, flame sensor and temperature sensor to detect fire occurred. In reality, the phenomenon of the fire may have smoke, flame and high temperature. Then we use rule based method to detect intruder, and fuse body sensors, ultrasonic sensors and IR sensors to detect intruder. Finally, we implement the fire detection system in the intelligent security robot (Chung-Cheng-I). If fire occurred, the security robot can find out the fire source using the fire detection system. In the intruder detection, we program the same scenario to detect the intruder using the intelligent security robot. The intelligent security robot transmits the message of detection result to the user using GSM modem for fire event and intruder, and transmits the detection result to client computer through Internet