Objective: A high-precision, low-cost quantitative and rapid detection method of nitrite in food based on photoelectric detection principle was proposed, and a portable nitrite detector equipped with microfluidic mixer chip was constructed. Methods: The microfluidic mixer chip was designed to realize the rapid mixing of test samples. The mixing efficiency of the chip was verified by peristaltic fluid simulation. The influence of UV curing parameters on the microfluidic mixer chip channel accuracy was analyzed, the microfluidic mixer chip was prepared. The photoelectric detection system of nitrite was designed and established. The relationship between nitrite content and induced voltage was analyzed, the detection sensitivity of the system was determined. Results: The detection limit of photoelectric detection system could reach 95.7 μg/L at a confidence factor of 3. The fitting error of the linear index of the system was 0.996 7, the average detection time was 3 min. Conclusion: The UV curing technology can realize the high-precision fabrication of microfluidic mixer chip. The detection accuracy and sensitivity of the self-developed photoelectric detection system can meet the requirements of nitrite detection in food.