Objective To observe and compare the effiacies of see and and three step strategy (cytology,colposcopy,and histology)for cervical intraepithelial neoplasia (CIN) and then to evaluate the advantages and disadvantages of the two methods.Methods The histopathological results of cytology,colposcopy,colposcopically directed biopsy(CDB),and LEEP in 629 patients with CIN treated by LEEP at Tongji Hospital and Maternity and Children's health Care Center of Foshan from January,2010 to January,2011 were retrospectively analyzed.Results The accuracy of CDB was 84.57%.CDB had some drawbacks that some patients be diagnosed with low grade CIN by CDB but with highly squamous intraepithelial neoplasia (HSIL) by postoperative pathology.Some patients with HSIL were chosen and treated by LEEP through see and method,and 16.43% patients were over-treated.The patients with HSIL confirmed by TCT,coupled with colposcopy and Reid score,weren' t over-treated in high RCI score group.Conclusions Most CIN can be found out buting cervical invasive carcinoma can't ruled out by CDB.See and for HSIL confirmed by TCT and colposcope is worth being clinically generalized,can make up for the inadequacy of CDB,maximumly improve the timeliness and diagnosis of CIN. Key words: Cervical intraepithelial neoplasia; Loop electrosurgical excision procedure; Colposcope; Colposcopically directed biopsy; See and treat