Underwater electrical wire explosion igniting energetic materials can generate stronger shock waves (SW), which is also considered as an important direction for the development of controllable shock wave technology. Compared with other energetic materials, the liquid-phase aluminum powder suspension has more advantages in terms of safety and uniformity that is easy to obtain and has a high reaction heat. It has great potential for civil applications. This paper reports an experimental study on the detonation of aluminum powder suspension by underwater electrical wire explosion. The aluminum powder suspension was confined in a plexiglass tube and passed through a 200 μm metal copper wire in the coaxial direction. After being driven by a high-voltage pulse source, it rapidly phased transformation and explosion, providing reaction conditions for aluminum powder. By comparing the discharge parameters and SW pressure signals of different quality aluminum powder suspensions, the electric explosion-driven aluminum powder discharge characteristics and the law of SW enhancement effect are obtained. The experiment shows that SW has two obvious peaks, which correspond to the evaporation SW (the first peak) and the breakup of the tube (the second peak). The effect of aluminum powder deflagration on the second SW is very significant. In the 300 mg aluminum powder suspension environment, the peak value of the second SW reaches 2.77 MPa, increased by 2.25 times compared to an optimal underwater electrical wire explosion, and the impulse of the SW is increased by about 50%. This paper also compares the SW signals in the suspension environment of 200 mg aluminum powder under different energy storage. It is found that with the increase of energy storage, both of two peaks of SW increase, reaching 3.17 MPa and 1.91 MPa respectively at 600 J. The impulse of SW also increases with the increase of energy storage. The impulse at 600 J energy storage is 41.12 Pa·s, which is twice as high as that at 300 J energy storage.