Objective To investigate the serum complement C1q/tumor necrosis factor-related protein 5 (CTRP5) levels in patients with community-acquired pneumonia (CAP) and its relationship with the levels of inflammatory cytokines. Methods A total of 80 patients with CAP who were inpatient in the Third People’s Hospital of Zhuji from January 2014 to December 2017 were selected as the CAP group. In the same period, 80 healthy people were used as the control group (C group). Accorded to the condition, CAP patients were divided into general CAP group (58 cases) and severe CAP group (22 cases). The serum CTRP5 levels and C-reactive protein (CRP), procalcitonin (PCT), interleukin-6 (IL-6) and tumor necrosis factor-ɑ (TNF-ɑ) levels were measured. Results Before treatment,the levels of serum CTRP5 and CRP, PCT, IL-6 and TNF-ɑ in the CAP group were higher than those in the C group (P < 0.05); the levels of serum CTRP5 and CRP, PCT, IL-6 and TNF-ɑ in the severe CAP group were higher than those in the general CAP group (P < 0.05).The serum CTRP5 level and CRP, PCT, IL-6 and TNF-ɑ levels after treatment in patients with general CAP and severe CAP were lower than those before treatment (P < 0.05). There was positive correlation between serum CTRP5 level and serum CRP (r = 0.521), PCT(r = 0.625), IL-6(r = 0.523) and TNF-ɑ(r = 0.584) levels in patients with CAP before treatment (P < 0.05). Conclusion The serum CTRP5 level of patients with CAP is elevated, and its level can reflect the severity of the disease and the degree of inflammation to a certain extent.