Objective · To analyze the clinical significance of colonization index (CI) for patients in emergency intensive care unit (EICU) to develop invasive candidiasis (IC) infection. Methods · Samples from patients admitted in EICU from February 2014 to January 2015 were collected, including sputum (or throat swabs), stool (or rectal swabs), midstream urine, skin swabs, and other samples. Samples were cultured with CHROMagar Candida chromagenic medium and Candida was isolated and primarily identified. Then detailed identification was performed by amplifying and sequencing the internal transcribed spacer (ITS) regions using the ITS1/ITS4 primers. Meanwhile, the clinical information of the patients was collected and the clinical significance of CI on monitoring the incidence of IC was analyzed. Results · A total of 111 patients were enrolled. Nine were infected with IC and 8 of them had Candida colonization before infection. The CI ≥0.5 group had significantly higher incidence of IC, mortality, and incidence of pyemia compared with the 0<CI<0.5 and CI=0 groups. Conclusion · The incidence of IC in patients in EICU is associated with the Candida colonization. CI can be used to reflect the Candida colonization in patients. Patients with CI ≥0.5 are more likely to have IC infection. Antifungal drugs and some invasive medical procedures such as central venous catheter (CVC) puncture, mechanical ventilation, renal replacement therapy, and surgeries are all risk factors for influencing Candida colonization and infection.