Many methods of fire detection in video have been carried out on PC. Generally it needs long cables to transmit images and processes videos on computers. That system is too dependent on computers, and costs a lot using cables to transmission. We would rather use a portable device to detect fire, which will bring us much more convenience. This paper designed a portable system to detect fire using DSP. The system integrates video acquisition, image processing and fire alarm together in a circuit board. Then we develop algorithms to recognize fire, and transplant them into DSP. Finally put it into use after commissioning test. This portable system can work independently. Users can put into their requirements through user-interface, and system will output the fire pictures and alarm by wireless communication or internet. This system is applicable to various places, such as indoor and outdoor, large and open spaces, forest, etc.