The invention provides a method using the quality-based utilization of low-rank 
coal to prepare 
natural gas. The method includes: 
drying, performing gasification reduction, performing desulfurization,preparing synthetic gas and preparing the 
natural gas. The method has the advantages that the 
raw material of the method mainly comes from the quality-based utilization process of the low-rank 
coal,high product additional value is achieved, and transportation is benefited; the synthetic gas is prepared by using 
coal-water 
slurry, and the reutilization of the low-rank coal solves the problem of environmental 
pollution; multi-approach gas preparation and high synthetic gas yield are achieved, the economic competiveness of gas preparation using the low-rank coal is enhanced greatly, and efficient, graded and comprehensive utilization of coal resources is achieved; the synthetic gas 
methane is prepared through the method, the method conforms to the industry policy of 
clean coal utilization and the current direction of 'turning coal into gas', pipeline transportation is facilitated, the problems that the low-rank coal is prone to dust raising and 
spontaneous combustion during transportation are solved, and by the quality-based and graded utilization of the low-rank coal, the coal is turned into the gas, west-east 
natural gas transmission is achieved, and energy self-supply is achieved.