Carbon foams (CFs), which can be manufactured from melamine foam (MF) via direct carbonization, are promising spacecraft thermal insulation material due to their excellent performance of sound absorption, low density, high porosity and heat resistance. Carbonization temperature, heating rate and carbonization time are three key elements during the melamine carbon foam process. As an improvement, this study simultaneously researches the impacts of pre-heat treatment on the microstructure, structure parameter, mechanical properties and heat-shielding performance of the melamine-derived carbon foam (MDCF), aiming to explore the best process of MDCF production. The results showed that the cross-linking degree and defects of MF samples were directly improved by pre-heat treatment. Additionally, all MDCF samples retained the three-dimensional mesh open-cell skeleton structure. The MDCF samples obtained by carbonization at 900 °C had the smallest average pore size structure, which performed the compressive stress of 16.8 kPa at 10 % strain and lowest thermal conductivity of 0.0252 W m−1 K−1. To further study the mechanical property and thermal conductivity performance of MDCF samples, the mechanics relationships of the buckling strength and shape variables, as well as thermal conductivity and pore size structure were researched.