Objective To observe the effects of breathing training guided by a WeChat‑based platform on the diaphragmatic function and postoperative recovery of elderly patients undergoing laparoscopic radical gastrectomy. Methods A total of 143 patients, 109 men and 41 women, aged 65‒80 years, American Society of Anesthesiologists (ASA) Ⅱ‒Ⅲ, who were scheduled for laparoscopic radical gastrectomy were enrolled. According to the random number table method, they were divided into three groups: a control group (group A, n=50), a preoperative breathing training group (group B, n=47) and a perioperative breathing training group (group C, n=46). Patients in group A were routinely given preoperative education. Group B participated in breathing training before surgery for at least 5 d in addition to preoperative education. Group C participated in breathing training for at least 5 d before surgery and 5 d after surgery, in addition to preoperative education. Patients in group B and group C were required to upload exercise videos in the WeChat group at the specific time every day. All patients underwent combined intravenous‑inhalation anesthesia. Their general information and intraoperative data (operation time, anesthesia time, intraoperative fluid volume, blood loss and urine volume) were recorded. Their hemodynamic indexes [mean arterial pressure (MAP), heart rate and oxygen saturation (SpO2)] were recorded before induction of anesthesia (T1) and at 1 h after the starting of surgery (T2). Their peak of airway pressure (Ppeak) and lung dynamic compliance (Cdyn) were recorded 10 min after anesthesia intubation (t1), 10 min after pneumoperitoneum (t2), 60 min after pneumoperitoneum (t3) and 10 min after the end of pneumoperitoneum (t4). Their diaphragmatic function [diaphragmatic mobility (DM) under calm breathing and maximum deep breathing] were recorded on the admission day (T0), T1, 30 min after extubation (T3), 1 d after surgery (T4), and 7 d after surgery (T5). Blood gas analysis parameters [pH, arterial blood partial pressure of oxygen (PaO2), and arterial blood partial pressure of carbon dioxide (PaCO2)] were recorded at T1, T4 and T5. The postoperative pulmonary complication (PPC) (pulmonary infection, atelectasis, pleural effusion and respiratory failure) within 7 d after surgery were recorded. The postoperative length of hospitalization stay, total length of hospitalization stay, and patient satisfaction score were recorded. Results Compared with group A and group B, PaO2 at T5 significantly increased in group C (P<0.05). Compared with group A: DM under maximum deep breathing at T1, T3, T4 and T5 increased in groups B and C (P<0.05), patient satisfaction scores improved in groups B and C (P<0.05), postoperative length of hospitalization stay and total length of hospitalization stay decreased in groups B and C (P<0.05), and the incidence of PPC within 7 d after surgery was significantly lower in group C (P<0.05). There were no statistical differences in other indicators among the groups (P>0.05). Conclusions Breathing training guided by a WeChat‑based platform can effectively improve the diaphragmatic function and promote postoperative recovery of elderly patients undergoing laparoscopic radical gastrectomy.