The invention relates to a preparation method of a coating containing TiB2 metal ceramic composite powder for a thermal spraying piston ring, belonging to the field of composite power body technology. The preparation method provided by the invention comprises the following steps: firstly, adopting a ball-milling method to perform mixing and wet grinding on 25-75wt.% TiB2 powder, 25-10wt.% NiCr alloy powder and 50-15wt.% Mo metal powder to obtain mixed powder with the particle size less than 3 micrometers; then mixing the mixed powder with adhesion agent PVA (Polyvinyl Alcohol), dispersing agent and deionized water in proportion in to slurry, performing atomization and granulation of the slurry at the drying temperature rang of 150-250 DEG C and under the atomizing disc frequency range of 140-190Hz through a spray drying device; and finally performing densification treatment on the powder through heat treatment technology and plasma balling technology. For the composite powder prepared by the preparation method of the invention, the particle size is uniformly distributed, the spherical degree, the densification degree and the mobility are good, the deposition efficiency of TiB2 can be improved, and the metal ceramic coating with good wear-resisting property can be prepared.