When the membrane wall water tubes and immersed tubes heat exchanger cannot effectively control the furnace temperature, arranging the horizontal tubes in the dilute phase is a method to solve the limited layout of the heat exchanger area. In order to study the heat transfer characteristics of the horizontal tubes in the dilute phase, the local and average heat transfer coefficients (HTC) were measured based on the pressurized fluidized bed apparatus under different pressures, particle sizes and gas velocities. The experimental results showed the improved heat transfer at elevated pressure and high gas velocities. The heat transfer tube with a lower height position had higher heat transfer coefficients because of the particle concentration effect. Under the same system pressure, the circumferential HTC of the horizontal tube were slightly higher at 0° and 180° circumferential positions, but the overall distribution tended to be uniform. Based on the experimental results, an empirical model for the average heat transfer coefficient prediction was developed and can predict 97.4% of the experimental data from this study and other different sources within 25% error with the absolute average deviation of 8.18%. This work can provide reliable experimental data for the design of heat exchanger tubes in dilute phase zone of pressurized fluidized bed and existing model verification. Also the correlation proposed in the paper can be translated to CFD code for further application.