In the Nui Beo underground coal mine, parameters of coal seams as thickness, dip angle, ash content, seam structure, etc., having specific influences on the system, especially in mechanizing technology in underground mining. Based on the analizing and statistical processing documents, results show that the coal seams are thick. The thickness of coal seams belong to an average group (4.26 m (V11)÷9.66 m (V7)) and their variations are relatively stable, dip angles are commonly less than 35 degrees, average from 17 to 20 degrees. Coal seams belong to a complicated structure. Parameters of the coal seams as the thickness, dip angle, coal seam structure, ash content, and other factors (hydrology and engineering geology, mine gas, etc.) are the factors that Influence the selection method of mining system and underground exploitation technology, in which thickness, dip angle, and structure of coal seams play a decisive role. Nui Beo mine has an area under residential area and under National Highway No.18A, which is also one factor that influences the selection of mining technology as well as method of controling the roof.