Reformer furnaces are widely used in a hydrogen plant to obtain hydrogen from hydrocarbon. The radiantt coils tubes are the most critical components of a reformer furnace, which can be heated up to 850 °C or higher temperature for long time during service. The failure of tubes usually happened before the designed life due to over-heating or unexpected damage, which usually leads to unplanned shutdown of plant and great losses. Thus, it is important to assess the damage conditions and residual life of furnace tubes. This study is an attempt to investigate the property degradation and residual life for service exposed reformer tubes of a hydrogen reformer furnace after 6 years service. Microstructural and mechanical experiments were carried out to reveal the property degradation, included optical observations, scanning electron microscope (SEM) observations, room temperature tensile tests, high temperature tensile tests, and stress rupture tests. Finite element analysis was also used to investigated the influence factors on the stress of tubes. The residual life of furnace tube was estimated based on these experimental and simulation results.