Objective To observe the effect of resistance breathing training on breast cancer related lymphedema. Methods Sixty breast cancer patients with lymphedema after operation from October, 2013 to April, 2015 were randomly divided into control group (n=30) and experiment group (n=30). The control group received routine rehabilitation and manual lymphatic drainage, while the experiment group received resistance breathing training in addition, for four weeks. Their flow of lymph was measured with emission computer tomography (ECT), and their upper arm circumferences were measured, their upper limb volumes were measured with water displacement before and after treatment. Results The flow of lymph increased in both groups after treatment (t>3.446, P<0.05), while the difference of bilateral upper arm circumferences (t>2.143, P<0.05) and upper limb volumes (t>1.562, P<0.05) reduced, and all the indices improved more in the experiment group than in the control group (t>1.982, P<0.05). Conclusion Resistance breathing training may increase the back flow of lymph, to relieve the lymphedema of injured extremity.