The invention concretely relates to a waste dump extinguishing method to solve problems of easy combustion resumption and generation of a large amount of harmful gases of present waste dumps. The method comprises the following steps: 1, initially grasping the spontaneous combustion case of a waste dump; 2, distributing points on the surface of the fire zone of the waste dump according to a 3-5m grid space, and calibrating and drafting an isothermal line and a gas isoline; 3, determining the depth of the fire zone or hidden combustion points; 4, carrying out waste dump classification and potential safety hazard screening, and treating in a zoning installment mode; 5, carrying out extinguishing cooling on the waste dump with naked fires, carrying out slope cutting, grading and packway construction on side slopes, and carrying out loess coverage; 6, punching and grouting, wherein a flushing solution used in punching is a colloid material, the end angle of a drill is 45DEG, and a composite gel extinguishing material is adopted as a grouting slurry; and 7, carrying out reclamation and ecological reconstruction according to a case that the loess layer thickness is 0.5-0.6m, the vibratory compaction frequency is 6-8, the compaction coefficient is 0.90-0.95, and green side slope plants adopt shrubs. The method has the advantages of elimination of threats of factors of landslip, harmful gas pollution and the like to residents, land reclamation, and repeated extinguishing investment reduction.