In this paper,HPLC eluting with trifluoroacetic acid(TFA) solution for theanine determination in white tea was compared to the national standard HPLC method(GB/T 23193-2008) with the pre-column derivation by o-phthaldialdehyde(OPA).The reference was Waters AccQ-Tag Kit.The results showed that theanine contents detected by HPLC method with TFA elution are more close to Waters AccQ-Tag kit,while GB/T 23293-2008 method had significant differences in a significant level of 5% compared to Waters AccQ-Tag kit.Furthermore,the derivative reaction time of GB/T 23193-2008 was investigated.It is found that the derivative products were stable in 15~20 minutes after OPA derivation and had a maximum response signal at 338nm.