Abstract: In order to investigate changing laws of tooth thickness of variable thickness scroll compressor quantificationally, a profile combined with the involute of circle, high curve and arc was proposed, and a mathematical model was established based on the geometric model to calculate the tooth thickness of a variable cross-section scroll tooth. The influence factors of tooth thickness were analyzed in detail by solving the mathematical model, and the relation between tooth thickness and profile parameters were established precisely. The research shows that the presented mathematical model can accurately describe changing laws of tooth thickness of variable cross-section scroll tooth, the size of tooth thickness as well as the initial position of variable tooth thickness can be quantitatively designed according to the design requirements, which provides the way of thinking for flexible design of scroll tooth. The mathematical model can also be applied to calculate the tooth thickness in other combination profiles.