Traditional tissue engineering scaffolds commonly consists of straight rods, inducing abrupt structure transition as well as large stress concentration on the rods’ intersections. Aiming to overcome this challenge, the triply periodic minimal surface (TPMS) scaffolds offer advantages like high surface area to volume ratio and less stress concentration with smooth surface joints. Especially, gradient porous scaffolds have received extensive attention in the research field of tissue engineering because they can provide an appropriate microenvironment for cell growth and tissue regeneration. However, there are only few studies on how to design the TPMS scaffold with gradient structure. In this paper, a parametric digital modeling method was utilized to design TPMS scaffolds, generating different kinds of gradient TPMS structures. The equivalent stress and strain of the proposed scaffolds were simulated by finite element (FE) models and the equivalent stress cloud diagrams under certain load conditions were obtained. The relations between the TPMS structure type, porosity, and the period number to the mechanical properties of the scaffolds were analyzed. Typical and gradient TPMS scaffold models were printed through FDM and SLA, validating the designing methods and the performance of the TPMS scaffold.