Being an important global reference rate of the money market，the reliability of LIBOＲ is vital． Nevertheless，the shortcomings of LIBOＲ fixing mechanism came under the spotlight during the LIBOＲ scandal in 2012． This paper focuses on the calculation of LIBOＲ fixing mechanism and compares the differences in the effects of mitigating manipulation under different LIBOＲ calculation methods by a model of LIBOＲ fixing with manipulation behavior． The results provide a theoretical basis for the fixing mechanism of IBOＲ-class rates，especially for Shibor． The main results are: From the perspective of mitigating total manipulation， trimmed mean method is not necessarily better than average mean method; the superiority of calculation methods depends on the market environment; for trimmed mean method，increasing the number of panel banks does not always decrease manipulation．