The invention belongs to the field of battery manufacturing, and particularly relates to a slurry coating process-based method for preparing a thin thermal battery positive electrode and electrolyte combination electrode piece. The method comprises the steps: preparing homogeneous thermal battery positive electrode slurry, then coating a conducting substrate with the homogeneous thermal battery positive electrode slurry, drying, solidifying and pressing to obtain a thin thermal battery positive electrode piece; and preparing homogeneous thermal battery fused salt electrolyte slurry, coating the thin thermal battery positive electrode piece with the homogeneous thermal battery fused salt electrolyte slurry in a lamination manner, drying, solidifying and pressing so as to obtain the thin thermal battery positive electrode and electrolyte combination electrode piece. The thin thermal battery positive electrode and electrolyte combination electrode piece prepared by adopting the method has the advantages that the thickness can be reduced by 1/3-1/2 and is adjustable in the range of tens of micrometers to hundreds of micrometers, and the combination electrode piece has very high values on creating a new way in miniaturizing and thinning thermal batteries and promoting development of national defense industries.