Objective To identify the independent predictors of severity and short-term outcome of stroke in young patients with acute ischemic stroke (AIS).Methods A total of 325 hospitalized young patients who were diagnosed with AIS from April 2013 to June 2015 were enrolled. These patients were divided into mild stroke group and severe stroke group according to their National Institutes of Health Stroke Scale (NIHSS) scores, and into good-outcome group and poor-outcome group according to their modified Rankin Scale (mRS) scores at 14 days after stroke. The baseline data and laboratory examination results were compared between groups.Results Compared with the mild stroke group, the severe stroke group showed significantly higher white blood cell count (WBC) and levels of globulin, blood glucose and fibrinogen (Fib) (P<0.05), but significantly lower levels of albumin, albumin/globulin (A/G) and free triiodothyronine (FT3) (P<0.05). Regression analysis indicated that high WBC (≥ 7.1×10⁹/L) and low FT3 level (<4.09 pmol/L) were independent predictors for severe stroke. Compared with the good-outcome group, the poor-outcome group showed higher WBC, levels of globulin, blood glucose, and Fib, and NIHSS score on admission, a longer length of hospital stay, and lower levels of albumin and FT3 and A/G. Regression analysis indicated that high WBC (≥ 7.1×10⁹/L), low A/G (<1.56), and low FT3 level (<4.09 pmol/L) were independent predictors for unfavorable short-term outcome.Conclusions In young patients with AIS, low FT3 level and high WBC are independent predictors for severe stroke, while low A/G and FT3 level and high WBC serve as independent predictors for unfavorable short-term outcomes.