A miniaturized ultrasonic sugar concentration detection system based on piezoelectric micromachined ultrasonic transducers (PMUTs) is presented in this work. An $8\times 9$ PMUT array together with a TDC1000 ultrasonic sensing analog front end is used to alternately transmit and receive ultrasonic signals. A PT1000 temperature sensor is employed for real-time monitoring the solution temperatures. The acquired and processed signals are sequentially subjected to ultrasonic time-of-flight (TOF), ultrasonic velocity, and sugar concentration calculations, followed by a temperature compensation by a microcontroller unit (MCU). A feasibility evaluation of the designed ultrasonic sugar concentration detection system is conducted. A sucrose solution is selected as the measurement sample. Measurement results show that the reported system can be used to determine sugar concentration in solutions well and can perform automatic temperature compensation. The reported ultrasonic sugar concentration system has a fast response of less than 1 s, an accuracy of 1.4%, and a high resolution of 0.6%, which is comparable to the classical optical saccharimeter. Furthermore, the reported system can be designed as a small catheter-based test probe with high portability for portable sugar concentration detections in food industry because of the compact size of the PMUT sensor.