In this article, discharge characteristics and hydrogen peroxide (H2O2) generation of multi-needles plate discharge under pulsed power are investigated. By changing the voltage peak value, the pulse repetition frequency, voltage rising edge time, and the number of needles, the change laws of discharge characteristics, molecular emission spectrum, and H2O2 concentration are studied. The results show that as the number of needles increases, the discharge power increases. Through the emission spectra showed, the emission spectrum intensity of OH ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{A}^{2}\sum + \to \,\,\text{X}^{2}\prod $ </tex-math></inline-formula> , 0–0, 309 nm) and N2 ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{C}^{3}\prod \text{u}~\to ~\text{B}^{3}\prod \text{g}$ </tex-math></inline-formula> , 0–0, 337 nm) also increases with the number of needles. The changes in the vibrational temperature and rotational temperature of N2 molecules show a steady process. As the number of needles increases, the vibrational temperature is 2835–3100 K and the rotational temperature is 342–410 K. They all belong to the low-temperature plasma range. As the number of needles increased, the concentration of H2O2 in the solution also increased. The concentration of H2O2 in the solution corresponds to the emission spectrum intensities of OH ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{A}^{2}\sum + \to \,\,\text{X}^{2}\prod$ </tex-math></inline-formula> ). When the peak value is 14 kV, the pulse frequency is 1 kHz. The maximum concentration of H2O2 reached 15.277 mg/L with 14 needles.