Micro-rib is regarded as an efficient method to regulate the heat transfer and thermal cracking of hydrocarbon fuel in regenerative cooling channels of advanced aero-engines. In order to explore the regulation mechanism of micro-ribs on heat transfer of endothermic hydrocarbon fuel with thermal cracking in the unilateral heated channels, a three three-dimensional simulation model including a 22-step cracking mechanism was built and experimentally tested. Besides, a macroscopic approach based on time scale analysis is proposed to estimate effects of obstacles on turbulence and thermal cracking. The studies demonstrated that due to unilateral heating, the regulation of micro-ribs on heat transfer and thermal cracking is non-uniform in the channel, relating to local turbulence intensity and fluid properties. Particularly, the thermal cracking of fuel responses more slowly than turbulence when meeting obstacles. In this case, the regulation of micro-ribs on the heat transfer characteristics of cracking hydrocarbon fuel is dominated by the direct perturbation of micro-ribs on flow momentum, not through promoting chemical absorption of thermal cracking by micro-ribs. Furthermore, higher fuel conversion and higher fluid temperature both assist the promotion of micro-ribs on thermal cracking to a limited extent but has little effect on the acceleration of micro-ribs on local turbulent flow.