This paper describes using spectrophotometer and ARM in food safety detection system. Using the spectrophotometer as sensors will convert lead concentration and organophosphate pesticides concentration into optical signals. Data will be analyzed by ARM. This system can also complete photoelectric conversion, A/D conversion functions and complete light signal processing effectively. The hardwares are low prices, cost-effective, stable work, and easy to operate. This testing technology provides a reliable method for food safety detection.