• The patient or his/her guardian is fully informed and agrees to participate in this clinical study and signs the informed consent form;

• At the time of signing the informed consent form, be over 3 years of age, regardless of gender;

• Patients with a confirmed diagnosis of acute B-cell leukemia/B-cell lymphoma/multiple myeloma who meet one of the following criteria:

∙ B diffuse large B-cell lymphoma (DLBCL), germinal center, or activated B-cell type; Primary cutaneous DLBCL; Primary mediastinal (thymic) large B-cell lymphoma; ALK anaplastic large B-cell lymphoma; High-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangement (i.e., double or triple hit); High-grade B-cell lymphoma; T-cell-rich B-cell lymphoma; transformed follicular lymphoma; or any aggressive B-cell lymphoma caused by indolent lymphoma; follicular lymphoma; mantle cell lymphoma; Patients with large cell transformation (Richter's Transformation) with CLL who have not achieved remission or have progressed after achieving remission after at least 1 prior line of therapy.

‣ Patients diagnosed with acute B-cell leukemia: Patients who have achieved relapse after achieving remission after prior chemotherapy; or patients who have failed to achieve remission (\<5% bone marrow blasts or persistent extramedullary or central nervous system disease) after 2 prior cycles of induction chemotherapy, or who still maintain MRD.

‣ Multiple Myeloma: Patients with confirmed diagnosis of multiple myeloma and patients with relapsed or refractory multiple myeloma according to IMWG 2016 diagnostic criteria.

• For patients with B-cell lymphoma, according to the recommendations for initial evaluation, staging, and response evaluation of Hodgkin and non-Hodgkin lymphoma (2014 edition), at least one measurable lesion in the baseline period, i.e., lymph node lesions with a length diameter of \> 15 mm, or an extranodal lesion with a length diameter of \> 10 mm according to PETCT or CT imaging;

• For patients with B-ALL, the proportion of bone marrow primitive and naïve lymphocytes in the screening period ≥5%;

• CD19 expression of tumor cells confirmed by flow cytometry or immunohistochemistry: the proportion of CD19 cells detected by peripheral blood flow cytometry in patients with B-ALL was ≥30%, and the proportion of CD19 cells in patients with B-cell lymphoma was positive by immunohistochemistry;

• Adequate function of vital organs: liver function satisfies ALT≤3×ULN, AST≤3×ULN; serum creatinine≤140μmol/L; Total bilirubin ≤ 2× ULN, and total bilirubin ≤ 3.0× ULN for patients with Gilbert syndrome; Haemodynamically stable and left ventricular ejection fraction (LVEF) ≥45% as determined by echocardiography or multichannel radionuclide angiography (MUGA); No active pulmonary infection, transcutaneous arterial oxygen saturation ≥92% in non-oxygen-based state;

• ECOG score: 0\

• 2 points;

• As judged by the investigator, the patient has an expected survival of more than 3 months;

⁃ Subjects of childbearing potential agree to use a reliable and effective method of contraception (excluding contraception during the safe period) for 2 years from the time of signing the informed consent form until receiving ECAR01 cell infusion.