Background: The incidence of Pneumocystis jirovecii pneumonia (PCP) has been increasing in patients with hematologic malignancies due to the use of glucocorticoid therapy and immunosuppressive medication. The reports of PCP in non-Hodgkin's lymphoma (NHL) after rituximab-based chemotherapy are still rare. We reported a case series of PCP in NHL to show the clinical features and prognosis in those patients. Methods: We conducted a retrospective review of 15 NHL patients who developed PCP after rituximab-based chemotherapy during June 30, 2014 to June 1, 2020. We analyzed the laboratory and radiographic findings for those patients through descriptive statistics analysis. Results: The study revealed that PCP in NHL patients was complicated by chemotherapy after about 4 courses (range, 2 to 6 courses). Most patients had a standard lymphocyte count before treatment, and 14 of 15 patients (93.3%) had lymphopenia at the time of diagnosis of PCP. In addition to typical symptoms such as fever and dyspnea at the diagnosis of PCP, most patients had abnormal laboratory indexes such as marked elevations of C-reactive protein (CRP) and lactic dehydrogenase (LDH) both before and at the time of diagnosis. The (1,3)-ß-D-glucan test was also revealed as a sensitive index for PCP. Bilateral ground-glass opacity was detected in 14 cases through computed tomography (CT) scans. Positive results of microbiological testing were observed in 7 cases; sputum culture was positive in 3 and next-generation sequencing (NGS) was positive in 3 of these 7 patients, and the other case was positive in both sputum culture and NGS. Patients received high-dose trimethoprim/sulfamethoxazole (TMP/SMZ), caspofungin, and steroids as the treatment for PCP. Ventilatory support was required by 3 patients, so they were admitted to the intensive care unit (ICU), and 1 patient died from PCP. Conclusions: Dynamic monitoring of CRP, LDH, and (1,3)-ß-D-glucan test during the treatment of NHL may have a predictive value for the diagnosis of PCP. Additionally, we should use NGS as a rapid and sensitive method for the early diagnosis of PCP. When patients are classified as 'probable PCP', early and effective treatment has obvious significance to improve the prognosis.