Abstract: Objective To investigate the expressions of KLF9， SP1 and HPV16／18 protein in ovarian serous or mucinous cystadenocarcinoma and their clinicopathological significance， and further investigate the effect of KLF9， SP1 and HPV16／18 on the occurrence and development of ovarian serous or mucinous cystadenocarcinoma. Methods Sixty cases of ovarian serous or mucinous mucinous cystadenocarcinoma and 20 cases of ovarian serous or mucinous cystadenoma were collected in this study. KLF9， SP1 and HPV16／18 were detected by immunohistochemical SP method and in situ hybridization. We also analyzed the relationship of their expression and clinicopathological features as well as the correlation among them. Results The positive rates of SP1， KLF9 and HPV16／18 were 71.7％（43／60），63.3％（38／60）and 30.0％（18／60） in ovarian serous or mucinous cystadenocarcinoma，higher than 15％（3／20）， 10％（2／20）and 0（0／20）in ovarian serous or mucinous cystadenoma （P＜0.05）. Spearman correlation showed that there was significantly positive correlation between KLF9 and SP1（r=0.443，P=0.000）， and also positive correlation between HPV16／18 and SP1（r=0.331，P=0.010）. The expression of KLF9 was not correlated with any clinicopathological features （P＞0.05）. The expression rate of SP1 was significantly correlated with clinical stage （P＜0.05）. The expression of HPV16／18 was correlated with pathological grade （P＜0.05）. Conclusion KLF9， SP1 and HPV16／18 were highly expressed and may affect the biological behavior of ovarian serous or mucinous cystadenocarcinoma. They may play an important role in the occurrence and development of ovarian serous or mucinous cystadenocarcinoma.