Tetra-n-butyl-ammonium bromide（TBAB）solution turns into clathrate hydrate slurry（CHS）when it is chilled in the temperature range of 0—12℃.This is well compatible with the temperature range of common air-conditioning operation.Thus，it is considered as an ideal heat-transport and cold-storage medium.Due to the phase change，TBAB slurry has far higher cold-loading density than water under the same temperature difference.Moreover，TBAB slurry behaves as fluid，so it can be easily transported through pipeline.Therefore，it is very promising to use TBAB slurry in air conditioning or district cooling system for its energy-saving advantages.In this paper，the heat transfer characteristics of TBAB slurry were investigated in a horizontal copper tube.The convectional heat transfer coefficients were measured and analyzed at different Reynolds numbers and constant heat flux.It was found that both the perturbation of solid particles and the decrease of apparent viscosity could destroy or thin the momentum boundary layer of slurry flow，which consequently contributed to a better heat transfer coefficient.The influence of volume fraction of solid phase（Φ）on Nusselt number seemed slight in spite of the change of Reynolds number.The comparison with references showed that the Nusselt numbers measured in CHS were consistently higher than those of the ice slurry and even single phase water. A correlation of Nusselt number with Reynolds number was presented.