Thermodynamic analysis and experiments of the steam reforming process of 1-methylnaphthalene as the tar model compound from coke oven gas (COG) were performed in this paper. In the thermodynamic analysis, as the temperature and steam/carbon (S/C) ratio rose, the hydrogen yield first increased and then flattened out yet with the compound completely converted and almost no coke deposition formed. In the experiments using a Ni/Mg catalyst with Ca12Al14O33 as a carrier, with the increases of the temperature and S/C ratio and the decrease of the methane-equivalent gas hourly space velocity (G(C1)HSV), the reforming result for hydrogen production became better gradually. After the temperature and S/C ratio increased to 800 degrees C and 12:1, respectively, and the G(C1)HSV decreased to 145 h(-1), the hydrogen yield and carbon conversion could reach over 90% and 97%, respectively, even very close to the thermodynamic values. Additionally, the catalytic stability and resistance to coke formation of the used catalyst also improved in such conditions.