Pixel-level digital integration detection is a new type of infrared detection technology with large charge processing capability and large dynamic range.It can effectively improve the detection sensitivity of infrared systems and has great application potential in various infrared weak signal detection fields.The twice quantization technique in pixel-level digital integration technology can effectively suppress the quantization noise that accounts for a large amount of total noise.This paper optimizes the quantization step size in the pixel-level digital integral detection system and studies the twice quantization technique,analyzes the influence of changing the quantization step size on the performance of pixel-level digital integral infrared detection system and the principle and characteristics of twice quantization,studies its key parameter design in application to promote the development of twice quantization technique in order to achieve higher sensitivity detection applications for pixel-level digital integration detection systems.