An appropriate concentration of micro/nano aluminum powder (MNAP) cloud is necessary for fuel air explosive (FAE) detonation. However, because of the fast dynamics, uncertainty interference, and transient characteristics of MNAP diffusion, experimental research on the measurement of MNAP cloud concentration is still lacking. Here, a pair of ultrasonic transducers were developed based on pulse drive, to measure the dynamic MNAP cloud concentration during MNAP diffusion in a standard 20-L explosion vessel. The measurement method was based on Lloyd-Berry ultrasonic attenuation theory. The experimental results showed that the ultrasonic pulse had a strong anti-interference ability, high precision, and real-time response to enable the characterization of MNAP diffusion concentration. The diffusion concentration gradients of MNAP were established and agreed well with the trend predicted by computational fluid dynamics simulations. The results also indicated that aluminum nanoparticles have better distribution characteristics than those of aluminum microparticles. These analyses provide technical support to improve FAE detonation energy. (C) 2020 Elsevier B.V. All rights reserved.