Abstract: In order to achieve the maximum network bandwidth utilization of FlexRay bus, the payload length in a FlexRay static frame was optimized. Based on a present optimization model for the static segment in a FlexRay network and by simplifying a nonlinear operator to a linear one, an analytical expression of the optimal static slot length was derived. The correctness of the expression was validated through numerical experiments and its applicable range was obtained. The research result shows that the optimal value of the payload length of a FlexRay static frame is proportional to the square root of the average length of all the static signals in a FlexRay network, and compared with a numerical method, the analytical expression increases calculation efficiency by 99%.