In this paper, without requiring the complete continuity of integral operators and the existence of upper-lower solutions, by means of the sum-type mixed monotone operator fixed point theorem based on the cone P h , we investigate a kind of p-Laplacian differential equation Riemann-Stieltjes integral boundary value problem involving a tempered fractional derivative. Not only the existence and uniqueness of positive solutions are obtained, but also we can construct successively sequences for approximating the unique positive solution. As an application of our fundamental aims, we offer a realistic example to illustrate the effectiveness and practicability of the main results.