The paper analyzed the pressures and the temperatures in compression chambers to calculate the bending fatigue strength for small parameter scroll wraps, and a load model is proposed. For the small parameter scroll wraps, the pressure loads can be simplified on the mid-areas and the temperatures are equal to the temperatures of the mid-areas. The pressure loads are of π-region pressures which have a normal angle interval of π, the number of acting regions for pressure loads is equal to the number of scroll compression chamber pairs. Apart from the part situated in the center compression chamber, the temperatures of scroll wrap decrease linearly with the normal angle. Selecting the reasonable discharge, specifying the appropriate material and the parameters, and modifying the starting part of scroll wrap are significant methods to improve fatigue strength of scroll wraps in practice.