As a high precision fluid measurement tool, ultrasonic flowmeter plays a significant role in energy saving. Based on Fluent software and used kε model, threedimensional (3D) flow fields in the table of ultrasonic flowmeter were simulated. By calculation and results analysis, K coefficient and its distribution law of standard deviation were obtained, how to choose the optimal sound path was discussed, as well as for the influence law of reflex column diameter and transducer high on flow characteristic of the table. The numercial simulation is helpful for structure optimization of the flowmeter.