Wild C₃ plant Reaumuria soongorica and C₄ plant Salsola passerina coexist mutually in some desert habitats and form large-scale communities distributed in northwestern China. In this study we collected their seedlings from the edge of the Tengger desert. Their seedlings were subjected to salt stress together by soaked in 0, 100, 200, 300 to 400 mmol/L NaCl solutions for 10 d. We examined their water contents and main mineral ion contents changes in their roots, stems, and leaves during salt stress. The experiment results indicated that S. passerina absorbed K and inhibited Na in leaves to adapt to high salt stress as NaCl concentration increased. By on the contrary, R. soongorica absorbed Na and inhibited K. Cl in its roots continuously increased two to five times higher than that in S. passerina's roots. Ca content in S. passerina roots was two to three times higher than that in R. soongorica roots. Si content in R. soongorica roots was three to five times higher than that in S. passerina. Therefore, salt stress resistance in R. soongorica and S. passerina communities occurred via root absorption of different ions, and these ions were subsequently distributed to various organs. Based on salt ion selective absorption coefficient S_{Na(leaf/root)/K(leaf/root)} ratio value, the two plants foliar selectivity increased K absorption and decreased Na absorption, thereby reducing salt damage on the leaves. Thus, these plants mutually benefit from each other and cooperate to promote their resistance to salt stress.