A quantum dot photoresist and a manufacturing method thereof, a display substrate and a display device are provided. The manufacturing method of the quantum dot photoresist includes: mixing quantum dots, photodiffusion materials and photoresist mother solution; surface treatment is carried out on the photodiffusion materials or the quantum dots. The quantum dot photoresist prepared by the manufacturing method of the quantum dot photoresist can be applied to the display device, and the photodiffusion materials can refract incident light to the quantum dots, so that light irradiated onto the quantum dots is increased, and thus, a problem of a low utilization rate of the incident light can be solved, and a display effect of the display device can be enhanced.