Objective: The aim of this study was to examine the efficacy of huperzine A (HupA), an isolate of Huperzine serrata, in the treatment of cognitive deficits in schizophrenia spectrum disorders. Methods: PubMed, PsycINFO, Embase, Cochrane Library, Cochrane Controlled Trials Register, WanFang, Chinese Biomedical, and China Journal Net databases were searched from inception to 15 July 2015 for randomized controlled trials (RCTs) in English or Chinese of HupA augmentation of antipsychotic drug therapy versus placebo or ongoing antipsychotic treatment. Results: Twelve RCTs (n = 1117) lasting 11.7 ± 6.0 weeks met inclusion criteria. All had been conducted in China. HupA outperformed comparators on the following outcome measures: the Wechsler Memory Scale-Revised including memory quotient (weighted mean difference (WMD: 10.59; 95% confidence interval (CI): 5.65, 15.53; p < 0.0001); Wechsler Adult Intelligence Scale-Revised including verbal intelligence quotient (IQ), performance IQ, and full IQ (WMD: 3.97 to 5.66; 95%CI: 0.20, 8.58; p = 0.01 to 0.00001); Wisconsin Card Sorting Test including response administer and non-perseverative errors (WMD: −12.79 to −12.29; 95%CI: −23.70, −0.88; p = 0.03 to 0.003). In studies using the Positive and Negative Syndrome Scale (n = 7)/Brief Psychiatric Rating Scale (n = 1), the differences in total score were significant (standard mean difference: −0.77; 95%CI: −1.27, −0.27; p = 0.002). All-cause discontinuation (risk ratio: 0.67; 95%CI: 0.36, 1.24; p = 0.20) and adverse events were similar between groups. Conclusions: This review suggests that adjunctive HupA is an effective choice for improving cognitive function for patients with schizophrenia spectrum disorders. More well-designed RCTs are needed to further confirm HupA's efficacy.