Six β-carboline alkaloids were isolated from a Chinese medicinal plant, Arenaria kansuensis MAXIM. (Chinese name: Xue ling zhi) (Caryophyllaceae), a very important Chinese folk medicine used to treat influenza, lung inflammation, jaundice, and rheumatism. However, no detailed studies have been reported on the chemical constituents of the plant. The structures of four new alkaloids named arenarines A, B, C, and D were identified based on spectral and chemical evidence, and two known β-carboline alkaloids were also identified.