The invention discloses high-stability colloidal foam for inhibiting oxidation self-heating of a loose 
coal body and a preparation method of the high-stability colloidal foam. The high-stability colloidal foam is prepared from the following raw materials in percentage by weight: 58-80% of water, 19-40% of 
fly ash, 0.4-0.8% of an air entraining agent, 0.2-0.6% of a 
film coating agent and 0.2-0.6% of a cross-linking agent. The preparation method of the high-stability colloidal foam comprises the following steps: firstly, weighing the 
fly ash and the 
film coating agent in proportion, adding the 
fly ash and the 
film coating agent into water, and fully stirring to obtain a uniform fly ash suspension; adding the air entraining agent into the fly ash suspension in proportion, quickly stirring for 5-10 minutes, and preparing fly ash foam through an air entraining foaming expansion process; and finally, adding the cross-linking agent in proportion, and stirring for 3-5 minutes to obtain the high-stability colloidal foam. The high-stability colloidal foam disclosed by the invention is good in heat-resistant stability and excellent in 
flame retardant property, can keep 
moisture for a long time and wet a 
coal body, has a good wrapping and bonding effect on loose 
coal bodies such as residual coal in a mine goaf, fire coal in a 
coal field fire area and the like, and can form a layer of 
coating film on the surface of the coal body to isolate 
oxygen for a long time.