The invention provides an application method for coking preventing of nano ceramic in a combustor of a cement rotary kiln. The hot isostatic pressing steeping is characterized by comprising the following steps that firstly, baking is conducted; secondly, cleaning is conducted; thirdly, spraying is conducted; fourthly, normal-temperature drying and curing are conducted; and fifthly, a pottery is formed through warming and sintering. By means of the design, a surface spraying nano ceramic material is adopted within 1 m of the head portion, and therefore blown sand and dust of a kiln head are prevented from being stacked and stuck to the head of the combustor, influences caused by combustor head coking and material stacking to roasting are fundamentally avoided, and stable production, the high yield and good quality of the rotary kiln are ensured. About 20,000 yuan needs to be cost by spraying the head by 1 m; and the output value is increased by about 1,000,000 yuan for 5000 tpd per kiln and per year by avoiding coking influences on 10% of the yield.