This paper investigates the stability of a class of nonlinear impulsive stochastic systems based on a novel dynamic event-triggered mechanism(DETM). To determine the instants of nonlinear impulsive control, a new DETM is designed, which dynamically adjusts the triggering threshold by introducing a fractional decay function. Compared with the DETM based on exponential decay functions, this mechanism results in fewer triggering times under the same conditions, lower control cost, and effectively avoids Zeno behavior. Compared with traditional linear impulsive control, the proposed nonlinear impulsive control strategy exhibits significant advantages in improving convergence speed and enhancing system robustness, and relaxes the constraints on impulse gains in traditional impulsive control. Furthermore, sufficient conditions for local asymptotic stability of nonlinear impulsive stochastic systems based on the DETM are proposed, and the results are extended to the cases of finite-time stability and finite-time contraction stability. Finally, the theoretical results are applied to a class of nonlinear impulsive stochastic systems, and both numerical comparative simulations and comparative simulations of Chua's circuit system are conducted to verify the effectiveness of the stability conditions and the superiority of the nonlinear impulsive control strategy.