The combination of ultrasound and microreactor is an emerging and promising area.Due to its non-invasive nature and strong acoustic effects like radiation force and streaming,ultrasound has been used widely to enhance mixing,accelerate chemical reactions and prevent clogging in microreactors.On the other hand,with well-defined micro-structure,microreactors provide an ideal environment to investigate and control the acoustic cavitation process,which is the main mechanism for most power ultrasound application.We have built a novel and highly efficient ultrasonic microreactor(USMR),and systematically investigated the mixing and gas-liquid mass transfer intensification in it.The prevention of solid particle fouling in microchannel was also studied.