A portable scanning surface plasmon resonance biosensor was constructed for the safety detection of food. The optical system, hardware circuit and software design were thoroughly introduced. The clenbuterol hydrochloride was used as samples, and the biological probe was fixed on the sensor chip. Clenbuterol hydrochloride antibody with different concentration as 2 mg/L, 4 mg/L, 8 mg/L,16 mg/L, and 32 mg/L were continuously detected. The experimental results accord with the immune response rule of biological molecules. The validity of this method and device was demonstrated by experiments. The device is portable and easy to operate. The device has extensive prospect in the safety detection of food.