Abstract: Aim at the problem of drawing annotation of how to use the profile tolerance to control the assembly gap and its uniformity, initially, taking the front and rear door assembly of a car as an example, the drawing annotation and application characteristics of the composite profile tolerance and multiple single-segment profile tolerance with additional "OZ" symbol when controlling the assembly gap were studied. Then, the panel and button assembly of a car were taken as an example to study the difference of the assembly clearance and its uniformity of the control surface with composite profile tolerance and multiple single-segment profile tolerance with additional "OZ" symbol. It was pointed out that the use of multiple single-segment profile tolerance with additional "OZ" was more effective than composite profile tolerance for controlling gap of closed/semi-closed or larger curvature surfaces. Finally, the specific application and detection method of the multiple single-segment profile tolerance with additional "OZ" symbol in the control of the gap between the fuel-tank cap and automobile body were analyzed. The research results can provide reference and reference for the control of surface clearance and uniformity, tolerance analysis and drawing annotation.