Objective: To analyze cost-effectiveness of morphine, MS contin and oxycodone in the treatment of cancer pain, providing guidance for rational drug use in the clinic. Methods: Confirmed by histology, a total of 171 patients with various cancers who required analgesic treatment were selected and divided into 3 groups, 57 cases for each group, given morphine, MS contin and oxycodone, respectively. If there appeared a poor short-term effect or aggravated sudden pain during the treatment, a short-acting morphine injection was given and adverse reactions were processed by symptomatic treatment. The pain relief rate and adverse reactions of groups were observed and pharmacoeconomics evaluation was undertaken. Results: The pain relief rates with morphine, MS contin and oxycodone were 89.5%(51/57), 91.2%(52/57) and 93.0%(53/57), respectively, with no difference samong groups (${chi}^2=4.4489$, P=0.6162). The occurrence rates of adverse reactions were 59.7%(34/57), 54.4%(31/57) and 43.9%(25/57), again with no significant variation (P>0.05). The ratios of cost-effectiveness (C/E) for the 3 groups were $14.6{pm}7.21$, $15.0{pm}7.44$ and $16.1{pm}8.10$. When the price of 3 kinds of analgesics was reduced by 10%, the ratios of cost-effectiveness were $12.2{pm}6.53$, ($13.4{pm}6.08$ and $14.5{pm}6.74$ but there was no differences when compared with before the price adjustment (t=1.86, P=0.0651; t=1.30, P=0.1948; t=1.17, P=0.2453). Conclusion: Morphine, MS contin and oxycodone give similar pain relief and adverse reaction rates but of all, morphine is the preferred drug for the treatment of cancer pain from the perspective of pharmacoeconomics.