This is a open,randomized phase II trial comparing effectiveness and safety of local use of rhGM-CSF and Compound Vitamin B12 to Compound Vitamin B12 solution alone treating oral mucositis in primary nasopharyngeal cancer. The main end point is the incidence of grade II and less oral mucositis at the end of treatment.The hypothesis of the study is that the local use of rhGM-CSF and Compound Vitamin B12 can decrease the incidence of grade III and more oral mucositis at the end of treatment compared to local use of Compound Vitamin B12 alone.

Inclusion Criteria:

1. Grade II oral mucositis induced by chemoradiotherapy in patient with primary nasopharyngeal carcinoma.
2. Receiving 68-72 Gray of radiation dose.
3. Age between 18 and 65 years.
4. KPS≥70.
5. Patient who has given his/her written consent before any specific procedure of the protocol.

Exclusion Criteria:

1. Severe uncontrolled infection.
2. Pregnant or breast-feeding females.
3. Allergy to this medicine.
4. Diarrhea.

Outcome measures:

1. Grade of oral mucositis:NCI Common Terminology Criteria for Adverse Events v3.0, NCI CTCAE v3.0
2. Pain: WHO,Numerical Rating Scale(NRS)
3. Tumor response to chemoradiotherapy:Response Evaluation Criteria in Solid Tumors,RECIST1.1

Inclusion Criteria:

1. Grade II oral mucositis induced by chemoradiotherapy in patient with primary nasopharyngeal carcinoma.
2. Receiving 68-72 Gray of radiation dose.
3. Age between 18 and 65 years.
4. KPS≥70.
5. Patient who has given his/her written consent before any specific procedure of the protocol.

Exclusion Criteria:

1. Severe uncontrolled infection.
2. Pregnant or breast-feeding females.
3. Allergy to this medicine.
4. Diarrhea.