Through analysizing the spatial distribution characteristics of the linewidth of Li-like si-licon ions X-ray lasers, we show that Stark broadening is the main line broadening me-chanism for Li-like Si11+ ions recombine X-ray laser. Spatial distribution of the electron den-sity of gain medium obtained by Stark brcadening shows that the electron density in the gain region is about 1019/cm3, and the lasing linewidth and electron density are 0.21? and 2.9 × l019/cm3 at the gain maximum respectively.