A triply periodic minimal surface (TPMS) is a surface-type microcellular structure expressed by trigonometric combinations of sinusoidal functions. TPMS structures are advantageous in their continuous internal channels and large surface areas. The recent development of additive manufacturing (AM) accelerates the advantages of the TPMS structure and is actively applied to applications as thermo-fluidic components. In this study, a novel design methodology was developed to functionally grade the morphology of a TPMS structure by mathematically changing the signed distance field (SDF) according to functional requirements. The proposed functional gradation was implemented in the design of a TPMS flow channel to reduce the flow resistance. Computational fluid dymanics (CFD) simulations were performed to analyze the flow sharateristics in the locally graded regions, and the simulation results were verified through flow visualization experiments using additively manufactured TPMS channels [1]. The developed gradation method was further applied to design of a TPMS-based heat exchanger (HX). Three gradation methods were proposed to fulfill the functional requirements of a plate-type HX: (i) selection filtering for the inlet and outlet, (ii) barrier filtering for controlling the flow direction, and (iii) boundary filtering for the reducing the flow resistance in the inlet and outlet. CFD simulations were conducted to investigate the effects of these gradation filters on the flow characteristics inside the TPMS channels. The optimal TPMS design was then additively manufactured, and heat exchange experiments were conducted to verify heat exchange capability [2]. Considering that a TPMS structure has a complex geometry and thus its manual modification is very difficult, the proposed gradation method provides an efficient approach for altering the morphology of the TPMS structure according to functional requirements of thermo-fluidic components.