To realize ultrasonic through metal thick wall effective communication, a transformerless high DC voltage ultrasonic transmitting system was designed. The power MOSFET tube IRF820 was used as the switch components,and incentive pulse signal was produced by FPGA, and MAX668 provided DC high voltage with 12 V single power supply, and base on those the design produced sharp pulse signal of 0.7 μs width and 256 V amplitude.The experiment showed that when high voltage sharp pulse signal by designed system produced stimulates transmitting transducer,it could get the ideal signal waveform at the receiving end of transducer.The design provided a solution for effective communication in sealed indoor which realized the information transmission rate with 10 kbps.