The present invention provides a novel method for preparing new type nanocomposite ceramics, which comprises the steps of that: (1) a polysilazanes precursor serves as the initial material and is subjected to cross linking and curing reaction at a temperature of below 260 DEG C in the presence of protective atmosphere; (2) the obtained amorphous state solid is added with catalyst and is subjected to high energy ball milling; (3)the crushed and uniformly mixed powder is loaded into an alumina crucible and then is put into an atmosphere furnace; (4) a pyrolysis reaction is carried out at 1100~1550 DEG C in the presence of protective atmosphere; (5) the powder is cooled in furnace to room temperature, and the single crystal low dimensional nanometer material is removed from the surface of the powder. Compared with the traditional technology, the present invention has the advantages of that a nanocomposite ceramics powder can be obtained, wherein the multimorphologies single crystal low dimensional nanometer material is grown in situ; the newly technology can keep the toughening reinforcement effect of the traditional fiber and crystal whisker, and can solve the problem of dispersion difficulty in the traditional technology. By adopting the followed agglomeration technology, the multimorphologies nanostructure synergistically toughened nanocomposite ceramics can be produced by the powder of the present invention.