Inclusion Criteria:  Age ≥18 years; Patients with relapsed/refractory marginal zone lymphoma or follicular lymphoma Eastern Cooperative Oncology Group (ECOG) Performance Status score 0-2; At least one measurable lesion by computerised tomography (CT) / magnetic resonance imaging (MRI) (the longest diameter of nodal lesion > 1.5 cm or extranodal lesion > 1 cm); Expected survival of more than 12 weeks;  Exclusion Criteria:  Having lymphoma with central nervous system (CNS) or cerebral pia mater invasion Known histologic transformation to aggressive lymphomas such as diffuse large B-cell lymphoma (DLBCL); Prior use of any phosphatidylinositol 3-kinase (PI3K) inhibitor or Bruton's tyrosine kinase (BTK) inhibitor Inadequate organ function of liver and kidney Currently known active infection with human immunodeficiency virus (HIV), hepatitis B virus (HBV) or hepatitis C virus (HCV) Having received systemic antitumor therapy or radiotherapy within 4 weeks prior to the first dose of the investigational product Toxicity of previous antitumor therapy not recovered to CTCAE grade ≤ 1, except alopecia, prior to the first dose of the investigational product Complicated with uncontrolled systemic infection requiring intravenous antibiotic treatment Pregnant (positive serum pregnancy test) or lactating women Any other disease, metabolic abnormality, physical examination abnormality or clinically significant laboratory test abnormality, one disease or state providing a reason to suspect that the subject is not suitable for HMPL-689 at the investigator's discretion, or one condition that will affect interpretation of the study results or bring the subject at high risk.