Objective：To obtain a set of aptamers of liver cancer serum markers by SELEX screening，and to provide new molecular biological detection method for the early diagnosis of liver cancer. Methods：Serum samples from 50 patients with primary hepatocellular carcinoma（HCC） and 50 normal serum samples of which physical examination showed no abnormalities were collected and mixed in equal proportions to prepare mixed sera of HCC and normal subjects. The serum was used as the target molecule for screening. Magnetic beads-normal human serum complex was combined with ssDNA library. The supernatant was then combined with magnetic beads-liver cancer serum to elute and isolate the specific ssDNA binding to serum of liver cancer. Nine rounds of ssDNA were screened by the method of the streptavidin biotin method，and transformed into PMD18-T vector. The single clones were selected and sequenced by Shanghai Biosystems. Affinity determination of serum tumor marker aptamers in patients was performed by flow cytometry. Results：After 9 rounds of screening，200 nucleic acid sequences were successfully isolated，of which 10 sequences were different. Specificity test showed that the binding dissociation constants of serum tumor marker aptamers and HCC serum were all in nanomolar level. Among them，Seq-1，Seq-16，Seq-17，Seq-56，Seq-72 aptamers could be bound to the serum of liver cancer with highly specificity，and could not bound to the normal serum. The positive rate of serum tumor marker aptamers was detected in 200 cases of liver cancer serum and 200 cases of normal human serum，positive detection rate was more than 91%. Conclusion：The use of a random single-stranded oligonucleotide library to successfully obtain an aptamer that specifically binds to liver cancer patient serum，and the obtained aptamer has the ability to antagonize liver cancer serum，which may provide a new convenient method for the early diagnosis of liver cancer.