Qu, P.H. Chen, Q. Fan, M.X. Gong, K.Y. Li, A.H. Li, B. Liu, H.C. Peng, J. Wang, Y. Wu, X.L. JACoW Publishing Geneva, Switzerland 2226-0366 978-3-95450-194-6 10.18429/JACoW-LINAC2018-THPO029 English 741-743 THPO029 cavity DTL operation simulation linac Contribution to a conference proceedings 2019 2019-01 https://doi.org/10.18429/JACoW-LINAC2018-THPO029 http://jacow.org/linac2018/papers/thpo029.pdf An Alvarez-type Drift tube linac (DTL) was utilized to accelerate the H⁻ ion beam of up to 15mA peak current from 3 to 80MeV of China Spallation neutron source (CSNS). For ease of manufacturing and measurement, the CSNS DTL was divided into four independent cavities. The Q factor of four cavities were given, including the measurement results of low-power[1] and high-power[2], and several reasons for the low Q factor of the cavity in the measurement process were analysed. During the op-eration of the DTL, the frequent alarm of the water flow switch causes the power of the cavity to fall to 0. Esti-mate the power loss of each component, under the cir-cumstances of ensuring adequate water flow, reduce the alarm threshold of the water flow switch of some compo-nents to improve the stability of the system.