Objective To analyze whether CYP2C19 gene and platelet testing guide ACS patients PCI benefit from postoperative dual antiplatelet escalation therapy. Methods Selecting ACS patients with 209 routine PCI surgery from January 2018 to January 2019 in Department of Cardiology, Third Affiliated Hospital of Guangzhou Medical University. Preoperative administration of aspirin 300mg and clopidogrel 600mg, and continued administration of clopidogrel 75mg/d and aspirin 100mg/d after operation. Genotype and light transmittance aggregation (LTA) was detected by gene chip 24 h after operation. According to genotype the remaining patients were divided into non loss of function (Non-LOF) alleles group Extensive-metabolisms (EMs) type, loss of function (LOF) alleles group as Intermediate metabolic (IMs) type and Poor-metabolisms (PMs) type. Define the maximum platelet aggregation rate (MPA)≥46% as hyperplatelet reactivity (HPR). The LOF group consisted of 23 patients who had both HPR and proclopidogrel and were upgraded to tigrillo for further treatment.The remaining patients without HPR who continued to be treated with clopidogrel comprised 90 patients in the LOF group without upgrade and 95 patients in the non-LOF group who continued to be treated with clopidogrel.Major adverse cardiovascular events (MACE) were recorded in the follow-up period of 1 year, and the incidence of MACE in the three groups was compared to determine whether gene and platelet detection could guide the benefit of dual anti-platelet upgrade therapy in ACS patients after PCI. Results There were 26 cases occurred during follow-up MACE, among which the incidence of unstable angina recurrence and overall MACE in the LOF allele-not-up group was the highest and significantly different compared with the Non-LOF allele group (P<0.05), there was no significant difference compared with the LOF allele-up group (0.05). while there was no significant difference between the Non-LOF allele and the LOF allele upgrading group (P>0.05). Conclusions Gene is an important factor in the difference of platelet reactivity and is associated with MACE. Upgraded treatments for high-risk patients screened for gene and platelet testing did not benefit.