The invention discloses a detection kit for capturing the gene copy number related to alpha thalassemia. The detection kit comprises capturing probes, the capturing probes are composed of 17 main probes and contrast probes, and the 17 main probes are designed for HBZ/HBZP1/HBA2/HBA1/HBQ1/HS-40 gene areas; the capturing probes conduct capturing and sequencing on target areas, the copy number of exons 1 and exons 3 of an HBA1 gene and HBA2 gene is estimated through data analysis, and the lacking types of genes are subjected to gene typing. It is verified through experiments that the kit can accurately detect the gene copy number related to alpha thalassemia and conduct typing on the lacking types, the detection sensitivity is 100%, the specificity is 99.89%, the precision is 96.55%, and theaccuracy is 99.90%. The problems are solved that for an existing method, the error rate is high, the stability is bad, the flux is low, the specificity is low, and particularly the high homology of the HBA1 gene and the HBA2 gene is not considered. The kit is also used for solving the problems that the homology of the HBA1 gene and the HBA2 gene is high, and multiple kinds of the lacking types exist and are difficultly distinguished.