To understand the role of silicon (Si) in alleviating sodium (Na) toxicity in Trifolium repens L. (white clover), the changes of biochemical and physiological parameters were investigated in four-week-old white clover seedlings exposed to 0 or 120 mM NaCl with or without 1.5 mM Si for 7 days. Results showed that added Si alone did not have any effects on the growth and Na⁺, K⁺ accumulations in white clover plants compared to the control (no added Si and NaCl). However, in the presence of NaCl, additional Si significantly enhanced the selective transport capacity for K⁺ over Na⁺ that contributed to reduced Na⁺ uptake and increased K⁺ uptake by roots, thereby improving its growth and K⁺/Na⁺ homeostasis in white clover. This study would provide a way for improving salt tolerance in important legume white clover forage.