Objective To investigate the feasibility of gastric tube-guided transanal decompression tube placement for the treatment of rectal cancer with obstruction. Methods We retrospectively analyzed the data of 55 patients with rectal cancer with obstruction undergoing placement of a decompression tube through the anus under the guidance of a gastric tube from January 2018 to February 2022. We calculated the success rate，the clinical remission rate of intestinal obstruction，and the incidence of complications including bleeding and perforation，and recorded their conditions within one year after surgery. Results Of the 55 patients，51 had successful tube placement，with a technical success rate of 92.7%；there were 47 cases of complete clinical remission，two cases of partial clinical remission，and two cases of no clinical remission，with a clinical success rate of 96.1%. One patient's tube detached due to an accidental pull three days after placement，and was successfully replaced. No bleeding or perforation was observed. Emergency open surgery was performed for one case of failed tube placement and two cases of poor decompression after tube placement，while elective surgery was performed for the remaining 52 patients（open surgery for 1 and laparoscopic-assisted surgery for 51）. Within one year after surgery，1 case developed liver metastasis，while the remaining 54 cases had no local recurrence or distant metastasis，and there were no deaths. Conclusion Under the guidance of a disposable gastric tube，a decompression tube can be inserted more efficiently and safely through the anus to effectively relieve intestinal obstruction caused by rectal cancer，which is suitable for promotion and application in primary medical institutions without digestive endoscopy equipment.