Abstract: An experimental apparatus of the liquid solid external circulating fluidized bed heat exchanger （LSECFBE）, which made use of nozzle as the particle circulating device, was established. An experiment for a wide range of variables by independently varying the conditions was carried out. The effects of liquid flow rate, nozzle diameter, nozzle position, particle diameter, initial charge of solids and liquid viscosity on the main pressure drop were studied. On the basis of these factors, an empirical equation for the main pressure drop was established. The values calculated from the empirical equation agreed well with the experimental values. It provides some theoretical information for the optimal design of the LSECFBE.