The invention discloses a construction method of a gene detection library of familial hypercholesterolemia and a gene detection kit and relates to gene mutation of LDLR (Low-Density Lipoprotein Receptor), APOB (Apolipoprotein B) and PCSK9 (Proprotein Convertase Subtilisin / Kexin type 9). In order to ensure that all target regions (including an entire coding region and an alternative splicing regionof a gene to be detected) are covered and prevent a primer dimer or a short segment from being formed between primers of adjacent amplicons, a PCR (Polymerase Chain Reaction) amplification primer isdivided into two independent primer pools; then primer sequence digestion, sequencing connector connection, library purification and quality detection are carried out; finally, the detection library is constructed. The method has the advantages that library establishment steps are simple and rapid, the cost is effectively reduced, the working amount is reduced, variation types are comprehensive, the detection accuracy reaches 100 percent and the flux is high.