Convection patterns in a mono-size granular system are studied experimentally in a 3D-cylindrical container under coupling vibration and airflow. The granular system has been changed from the non-fluidized state to the fluidized state with increasing the air velocity. The phase diagrams of particle convection in four different particle size systems are provided. When decreasing vibration frequency (f = 15-45 Hz), increasing vibration acceleration (Gamma = 2-7), or increasing air velocity (u = 0-1.81 m/s), particle convection shows three patterns in turn: one pair of rolls, one single local roll, and one single global roll. These convection patterns can be observed when particle size is increased from 2 mm to 8 mm. However, the pattern forming conditions of vibration and airflow are different with the change of particle size. Particle convection depends strongly on vibration and airflow parameters, and the convection intensity is enhanced when the convection pattern changes from one pair of rolls to one single global roll. The convection intensity has a close relationship with convection patterns. (C) 2018 Elsevier B.V. All rights reserved.