Ultrasonic velocity profile monitor (UVP) for the flow metering system has been developed. The principle of this system is based on the integration of instantaneous velocity profiles over a pipe diameter. This system is expected to be able to eliminate installation problems such as entry length as well as to follow transient flow rate precisely. In the previous study, the authors reported the results of multi-line flow rate measurement employing this method. However, the previous multi-line measurement requires a lot of ultrasonic transducers. Therefore the system was high cost performance and complicated. From this fact, the authors developed the ultrasonic array transducer for multi-line velocity profile measurements. The array transducer has 128ch elements on the same surface of the transducer. It is very useful techniques because it can measure cross section image using only one transducer. In this study the authors developed multi-line velocity profile measurement system in rectangular channel using UVP DUO with the array transducer. Furthermore the authors applied the array transducer to two phase flow measurements.