Objective:To analyze the effect of morphine hydrochloride sustained-release tablets given by different administration routes on patients with cancer pain.Methods: Chosen patients with cancer pain as research subjects, underwent morphine hydrochloride sustained-release tablets for treatment of pain, randomized to receive oral administration as control group and rectally administration as observation group, observed pain relief degree, onset time of analgesia and adverse reaction rates.Results:1)After treatment, the observation group patients’ overall response rate was 94.05%,no significant difference compared with the control group; 2) After treatment, the observation group patients had a mean onset time (0.68 ±0.17) h, significantly shorter than the control group,0.5h, 1h, 2h, 4h of onset percentages of analgesia were higher than control group; 3)After treatment, the observation group patients’ incidence of adverse reactions was 2.38%, significantly lower than the control group.Conclusion: The morphine hydrochloride sustained release tablets rectal administration route can significantly alleviate cancer pain, shorten onset time of analgesia, and don’t increase the incidence of adverse reactions.