Land-based circular tank recirculating aquaculture systems, which offer advantages such as water conservation, environmental sustainability, and low cost, are increasingly emerging as a significant trend in modern aquaculture. The hydrodynamic characteristics within the tank directly influence the accumulation of residual feed and fecal matter as well as water quality fluctuations, while the airlift water jets plays a crucial role in enhancing these conditions. A field test was conducted to investigate the hydrodynamic characteristics of a large-scale, land-based circular tank under the influence of the airlift water jets. Three deployment angles for the jet were evaluated, defined as the relative angle between the jet direction and the tank wall (θ=0°, 20°, and 45°), and for each deployment angle, the number of airlift water jets was varied across seven levels (n=2, 3, 4, 6, 8, 10, and 12). An acoustic Doppler velocimeter was employed to measure the velocity distribution in three distinct water depth of the tank (located at h=30 cm, 60 cm, and 90 cm from the surface), and the hydrodynamic characteristics were evaluated based on the average velocity (v_avg) and the tank uniformity coefficient (U). The results indicated that the configuration of the airlift water jet exerts a significant influence on the flow field and hydrodynamic properties. When 12 jets were installed at an deployment angle of 0°, a large low-velocity zone was observed at the center of the tank. As the deployment angle increased from 20° to 45°, the area of the low-velocity zone within the tank progressively decreased. At an deployment angle of 45°, the average velocity under each operating condition is 0.051 m/s, and the tank uniformity coefficient is 0.29, resulting in the most uniform flow field distribution and a markedly expanded high-velocity zone within the tank. Moreover, at an deployment angle of 45°, when the number of airlift water jets exceeded two, further variations in jet count did not produce a significant impact on the flow field distribution. In summary, the installation angle exerts a more pronounced effect on the flow field within the tank than variations in jet count, and these findings offer a theoretical basis for optimizing the configuration of airlift water jets in large-scale circular aquaculture tanks.