Abstract: [Objective] The technique and effect of minimally invasive treatment of humeral shaft fracture in adults with elastic intramedullary nail are introduced.[Methods]From January 2019 - March 2020, 60 adult patients with humerus shaft fracture were treated with minimally invasive flexible intramedullary nail with fine access road.Accurate Angle needle insertion, scientific configuration of intramedullary nail, excellent reduction and reliable stability.[results] The intraoperative blood loss was 0ml-10ml, with an average of 3.63±1.14ml; the operative time was 15min-25min, with an average of 19.45±2.33min; the fractures all reached the standard of functional reduction; the clinical healing time was 8-16 weeks, with an average of 10.30±1.43 weeks; the bone healing time was 12-20 weeks, with an average of 15.30±1.65 weeks; no postoperative complications occurred; the neER score of shoulder joint and the Mayo score of elbow joint at 12 weeks:The excellent and good rate was 100%, the function of upper limbs was completely normal, all the patients were cured and the effective rate was 100%.[conclusion] Minimally invasive treatment of humeral shaft fractures in adults with fine access road elastic intramedullary nail has the advantages of small trauma, short operative time, simple reduction, stable fixation, quick healing, no complications, good functional recovery and so on.