Abstract: Objective To evaluate the characteristics of dosimetry and clinical efficiencies of domestic medical linear accelerator， and provide dosimetry basis for the clinical application of domestic linac. Methods Eleven patients were selected after breast conserving surgery who need to adjuvant radiotherapy， including 5 right breast cancer patients and 6 left breast cancer patients. The prescription dose was 50Gy／25f. Each patient performed dynamic intensity modulated radio-therapy （dIMRT） and three-dimensional conformal radiotherapy（3D-CRT） by TIGRT TPS. The dose volume histograms （DVHs） were used to analyze the characteristics of dosimetry on target volume and the organs at risk （OARs）， and the conformity index （CI） and homogeneity index （HI） were calculated. The monitor unit （MU） and performing time was recorded. Results There was similar coverage of target dose between dIMRT and 3D-CRT. D95 and V100 of dIMRT and 3D-CRT plan were （5009.73±12.70）cGy， （95.41±0.54）％ and （5005.47±7.30）cGy， （95.18±0.28）％. D2, CI and HI of dIMRT and 3D-CRT plan were （5551.66±89.21）cGy, 0.83±0.01，1.10±0.02 and （5819.20±111.19）cGy, 0.52±0.05， 1.14±0.02，with significant differences（P＜0.05）. V5, V10 and V20 of patients with ipsilateral lung of dIMRT was （65.32±5.88）%, （38.99±14.42）% and （17.76±0.43）%, which was significantly higher than that of 3D-CRT plan（P＜0.05）. V30of patients with ipsilateral lung of dIMRT plan was（5.59±1.52）％，which was significantly lower than that of 3D-CRT plan，with significant differences（P＜0.05）. Dmeanof left breast cancer patients heart in dIMRT plan was（814.59±154.82）cGy， which was higher than that in 3D-CRT plan， with significant differences（P＜0.05）； Dmaxof left breast cancer patient’s heart in dIMRT plan was（4067.93±441.39）cGy， which was lower than that in 3D-CRT plan， with significant differences（P＜0.05）. Dmax and Dmeanof right breast cancer patient’s heart in 3D-CRT plan were（56.34±15.56）cGy and（393.00±94.95）cGy，which were lower than those in dIMRT plan， with significant differences（P＜0.05）. MU and treatment delivery time of dIMRT plan was 593.17±39.27 and （124.57±8.25）s，while that in 3D-CRT plan was 639.50±49.81 and （134.30±10.46）s. Conclusion Domestic linac can be perform well in rediotherapy for early stage cancer after breastconserving surgery， and dIMRT with good at CI and HI， 3D-CRT has lower sparing at OARs.