Abstract: In this paper, a nucleic acid protein analyzer based on Lambert-Beer law and ultraviolet spectrophotometry is introduced, which is composed of ultraviolet monochromatic light generator, photoelectric signal detection module, vortex mixer, touch screen and embedded central controller. For ultra-micro measurement, a continuous-wavelength full-spectrum spectrophotometric detection circuit is designed in the hardware part. The transmitted light signal is collected by silicon photodiode, amplified and processed by subsequent circuit, and then transmitted to a single chip computer STM32F407VGT6 with CortexTM-M4 core after A/D conversion. The concentration and purity of nucleic acid protein are evaluated by assistant software detection algorithm. The instrument has the characteristics of compact size, flexible use, simple operation, high sensitivity and high detection efficiency. The experimental results show that the instrument has good sensitivity, repeatability and accuracy, and is suitable for the ultra-micro measurement of nucleic acid sample concentration, purity and protein concentration.