Neutrino oscillation experiments are able to test the CPT conservation by measuring the masses and mixing parameters of neutrino and antineutrino. In this poster, we will present the study on CPT testing based on the fake data combination of T2K2, NOvA2 and JUNO. The synergy of the three experiments will give the world best bound on CPT violation, in which the bound on $delta(Delta m^2_{31})$ is improved by at least one order compared to the current values.