Tetra-n-butyl ammonium bromide (TBAB) is an attractive additive to form hydrates that can incorporate specific guest molecules, such as CO2, and the phase diagram of CO2 + TBAB double hydrate is important to the formation and dissociation of hydrate. In this work, experimental equilibrium data of CO2 + TBAB hydrate are presented in the pressure range of (0.3 to 4.4) MPa and in the temperature range of (279 to 292) K at mass fraction w = 0.05, 0.10, 0.19, 0.32, and 0.55. Meanwhile, the visualization of TBAB hydrates with and without CO2 is also presented and discussed.