Iodine test coloring refers to soaking the cervix with an iodine solution and observing the changes in the cervical epithelium after 30 seconds. If the epithelium changes to a brownish color, it is called an iodine test (+), which indicates that the patient’s epithelium of the cervix is a mature squamous epithelium and is normal. If the cervix does not change color, it is called iodine test (-), which is often seen in the cervix with atypical epithelium or cancerous epithelium, and it is necessary to carry out a biopsy under the colposcope on the uncolored parts or suspicious parts, and do the pathological tests on the tissues, in order to diagnose the cervix with or without lesions clearly.