This is a randomized, double-blind, placebo-controlled, single dose escalating, study in 5 sequential cohorts to investigate the effect of a single s.c. injection of SHR-1314 at 5 dose levels (20mg, 40mg, 80mg, 160mg, and 240mg) in healthy subjects. Each cohort will consist of 6 subjects receiving active drug and 2 subjects receiving placebo, for a total of approximately 40 subjects dosed at one study site.