Organ transplantation has become a powerful strategy for the treatment of malignant diseases. Nevertheless, graft rejection is one of the main factors affecting graft survival after organ transplantation. Under this circumstance, the transplant-related mortality still keeps up. This invention includes the precise medication guidance of Tacrolimus (FK506) inapplicable population, against the side-effects of this drug. This invention, based on second-generation sequencing, has the advantages of relatively low cost and high sequencing throughput. During the design process, we collect the data of single nucleotide polymorphism (SNP) concerning the adverse drug reactions of Tacrolimus. Then we filter and summarize fifteen SNPs basing on importance degree (level >key enzyme>race). Thenceforth, after the process of analyzing the raw extract by operating BWA, Picard-tools, GATK, and Perl, we annotate SNPs by Annovar. Through this innovation, people can obtain further feedback on drugs that targets different genes in order to achieve the purpose of precision medication and minimizing the risks of misusing Tacrolimus.