In the detection of the concentration of the solution system of ultrasonic time difference method, only the detection precision time parameter reaches microsecond, which influence the accuracy of the system, in order to improve the detection accuracy of solution concentration, the ultrasonic phase difference method to detect the concentration of the solution. Based on the ultrasonic phase difference model, with MSP430F2272 MCU as the processor, dual ultrasonic transceiver for detection device design solution concentration measurement system of ultrasonic, the digital phase detector AD9901 ultrasonic detection by standard sample solution and the solution to be measured by the corresponding phase difference, converted by the SCM calculated concentration. The experiment shows that the system error is less than 1%, and the device has stable performance and simple structure, which meets the requirements of the expected design.