In this paper, a novel type of in-fiber optofluidic Raman self-assembly graphene oxide (GO)/PDDA/Ag NPs SERS sensor for the adenine in DNA is proposed. The microstructured hollow fiber (MHF) has a channel and a suspended core in microscale, which allows the sample to flow into the fiber. Meanwhile, the GO/PDDA/Ag NPs SERS substrates are modified on the MHF core by chemical bond. When the sample is interacted with the evanescent field excited by the suspended core, the on-line SERS signals can be coupled back to the core and be detected. Here, we carry out on-line optofluidic detection on the adenine samples. The results show that the detection limit (LOD) of the samples of is about 1 x 10(-14) M. The unwound DNA solution extracted from biological blood is injected into the MHF. Under the action of the hydrogen bond between PDDA with adenine, the adenine base in DNA is successfully detected and the interference of guanine, cytosine and thymine is eliminated. Significantly, this work provides an integrated self-assembled GO/PDDA/Ag NPs SERS adenine sensor in an optofluidic fiber. This rapid, convenient and sensitive Raman detection sensor of adenine in DNA is expected to have more potential applications in HIV, genetics and other fields.