Electronic Journal of Differential Equations, Vol. 2025 (2025), No. 40, pp. 1-16. Title: Random attractors and their stability for nonclassical diffusion equations driven by additive white noise with delay and intensity Authors: Wenhui Ma (Northwest Normal Univ., Lanzhou, China) Qiaozhen Ma (Northwest Normal Univ., Lanzhou, China) Abstract: In this article, we study the asymptotic behavior of solutions of nonclassical diffusion equation driven by an additive noise with delay and intensity $\epsilon\in(0,1]$ on $\mathbb{R}^n$. We first establish the existence and uniqueness of tempered pullback random attractors for the equations in $C([-\rho,0],H^{1}(\mathbb{R}^n))$, and then the upper semicontinuity of random attractors is also obtained when the intensity of noise approaches zero. It's worth mentioning that the Arzela-Ascoli theorem, spectral decomposition, and uniform tail-estimates have been utilized to demonstrate the asymptotic compactness of the solutions. Submitted October 2, 2024. Published April 11, 2025. Math Subject Classifications: 35B40, 35B41, 35R60, 37L55. Key Words: Pullback random attractors; nonclassical diffusion equation; nonlinear delay; additive white noise