(A) Initial treatment of patients with CML in chronic phase 1. TKI therapy: TKI is the preferred treatment for patients in chronic phase, and the first iteration of imatinib 400 mg. is recommended once daily (Figure I). During the treatment period, hematologic, cytologic and molecular genetic responses are monitored regularly, and the response to treatment is evaluated with reference to the treatment response criteria for CML patients with Chinese characteristics (Table 1), and the treatment regimen is adjusted at any time. Early molecular response is crucial, especially the level of BCR-ABL fusion gene at 3 months of imatinib treatment. Clinical treatment response included best response, suboptimal response by Sun Zhiqiang, Department of Hematology, Affiliated Hospital of Guizhou Medical University, and treatment failure. Patients with suboptimal response and treatment failure should be evaluated for treatment compliance, patient tolerance, and combined medications based on timely BCR-ABL kinase region mutation testing and timely replacement of second-generation TKI such as nilotinib or dasatinib, and patients with suitable donors can be considered for all–HSCT. Good adherence education and close monitoring are important for optimal clinical outcomes. 2. Other treatments: interferon-based regimens and allo-HSCT can also be used in the chronic phase of CML, as described in the next section. （If the patient has a suitable source of hematopoietic cells, allo-HS CT’ can be considered. Patients with T3151 mutation or second-generation TKI insensitive mutation should undergo allo-HSCT as early as possible, and new drug trials are feasible for those who are eligible for new drug clinical trials. 2. Treatment of acute changes: Referring to the patient’s previous treatment history, underlying disease and mutation, choose TKI monotherapy or combination chemotherapy to improve the induction remission rate, and perform allo-HSCT as soon as possible after remission, and perform new drug trials in units that are qualified to perform new drug clinical trials. The choice of second-generation TKI For patients who are intolerant, respond poorly or fail to imatinib treatment, consider switching to a second-generation TKI, currently the second-generation TKI available in China are nilotinib and dasatinib, both of which have similar therapeutic effects on patients with different stages of CML, but both have significantly different pharmacokinetics, drug interactions and adverse effects. The patient’s medical history, comorbidities, combined medications, adverse drug reactions and drug instructions should be taken into consideration and combined with the BCR-ABL kinase mutation type for selection. 2. Refer to the type of BCR-ABL kinase mutation: the following seven types of mutations have clear guidance for the selection of nilotinib or dasatinib: ①T3151: both are resistant, and those who are eligible can enter clinical trials or choose appropriate treatment regimens; ②F317 UV/I/C, V299L, T315A: treatment with nilotinib is more likely to achieve clinical efficacy. (iii) Y253H, E255 K/V, F359C/V/I: clinical efficacy is more likely to be achieved by choosing dasatinib.