  We study a frustrated two-dimensional lattice spin model with Kitaev type
interaction. The lattice is obtained from the honeycomb lattice by replacing
half of its sites with triangles. Using the SO(3) Majorana representation of
spin, the model is exactly mapped into a $Z_{2}$ lattice gauge theory of
complex fermions with standard Gauss law constraint. We show that the ground
state of the model is a chiral spin liquid, and it has gapless excitations. The
Chern number of the ground state is $\pm 1$, implying the existence of chiral
edge mode. The vortex excitation of the model is bound with a Majorana zero
mode, such mode behaves as non-Abelian anyons.
