In this article, we apply blow-up analysis to study pointwise a priori estimates for some p-Laplacian equations based on Liouville type theorems. With newly developed techniques, first extend the classical results of interior gradient harmonic function that p-harmonic function, i.e., solution Δpu = 0, x ∈ Ω. We then obtain singularity and decay sign-changing Lane-Emden-Fowler equation −Δpu |u|λ...