Objective To assess oncology nurses′ practices regarding oral assessment for patients on radiochemotherapy treatment, and to provide reference for standardizing oral assessment and preventing oral complications. Methods A total of 198 oncology nurses were selected by convenience sampling and were invited to complete a questionnaire survey in terms of their practices regarding oral assessment for patients on radiochemotherapy treatment. Results Only 12.63% of the respondents performed oral assessment for patients initially receiving radiochemotherapy before the occurrence of oral complications and 12.63% of them used assessment tools. About 97.98% of the nurses conducted oral assessment when patients developed oral complications and 46.97% used assessment tools. More than forty percent (42.93%) of the nurses performed oral assessment for rehospitalized patients and 10.10% used assessment tools. Conclusion Nurses paid less attention to oral assessment for patients without oral complications before radiochemotherapy treatment and for those who were rehospitalized for treatment, and they generally were inadequate to perform oral assessment. At the same time, there was a shortage of targeted oral assessment tool. Oral assessment should be strengthened in patients before radiochemotherapy treatment and in rehospitalized patients. The assessment contents and process should be improved as well as the assessment tool should be designed.