Spatial expansion is the ecological adaptation and trade-off decision of clonal plants in response to the environment. In order to study the spatial expansion strategy of clonal architectures and its response to soil environmental factors under heterogeneous conditions, Phragmites australis in Yangguan National Nature Reserve (Dunhuang, China) with a typical inland salt marsh wetland was selected as the research object. Three different sampling sites including near water zone (500 m), transition zone (1500 m) and desert zone (2500 m) were set up. The results showed that:(1) The features of the clonal architectures of Phragmites australis differed significantly in heterogeneous environment, and the co-evolutionary relationship of architectures showed significantly positive correlation with the primary rhizome number, rhizome internode length, spacer length and branch angle (P < 0.01), and negative correlation with the ramet number (P < 0.01). (2) Phragmites australis presented a survival strategy from "phalanx" to "guerrilla" during spatial expansion with gradual decreases of population density. (3) Soil water, pH value and salt were the main driving forces of spatial expansion of clonal architectures based on redundancy analysis. Specifically, water in each soil layer, pH value and salt in deep soil were the most important soil environmental factors driving the spatial expansion of Phragmites australis. This study provides a scientific basis and case reference for protection management and ecological restoration of inland river wetlands.