a thermoforming machine with accurate process and heater control for the forming process was used in this study. the forming system and test film are shown in fig2. for dimensional measurement, a precision imaging measuring system equipped with 2um encodes and the Q-16 metrology was used to measure the formed film. the thickness gauge. in order to understand the effect of forming conditions during thermoforming processing, a variety of forming parameters including mold temperature,film pre-heating temperature, plug depth and plug holding time were used in this study. in addition to these investigations, another important study regarding material properties involve stretching ratio, variation rate of film thickness, residual stress, as well as part surface quality, was also discussed via one-step forming. for measurement of each variation in dimension and thickness, five samples formed under the same forming conditions were used. then the average value of the five tested results was used for analysis and correlation. the methods of measuring dimension and thickness variation are described and given as follows.