To provide convenience for the translation among specimens, orthogonal experimental method was used to research the relationship between geometrical dimensions （length, width and thickness） and total elongation of polycarhonate sheet, and simulations of tensile specimens with different geometrical dimensions had been conduc- ted by the finite element method, then regression analysis method was used to create the relationship formula be- tween geometrical dimensions and total elongation. It was found that： the shorter the length of specimen is, the better the plasticity is, and they had the power exponent relationship; the larger the width and thickness are, the better the plasticity is, and they had the direct proportion relationship with the total elongation.
