The invention discloses ctDNA library construction and sequencing data analysis methods for simultaneously detecting common mutations of various liver cancers. The library construction method and thesequencing data analysis method have the following advantages: firstly, various mutation forms of liver cancers are simultaneously detected under the condition that capture is not needed; secondly, the methods are suitable for efficient capturing in an ultra-small target area; thirdly, the library can support 10 to 20 times of detection; fourthly, the DNA barcode is connected to an initial ctDNA molecule during the library construction process and the flow is analyzed by cooperating with a biological information analysis process to realize high-specificity detection of ctDNA low-frequency mutation; and fifthly, the library can be used for PCR hot spot detection and capture method sequencing at the same time, the false positive mutation can be filtered effectively by using the added DNA barcode to realize duplex-based high-specificity sequencing. The methods have the important clinical significance for early screening, disease tracking, curative effect evaluation, prognosis prediction and the like of liver cancers.