The crystallographic orientations of m-plane ZnO on (112) LaAlO3 (LAO) substrate are ZnO||LAO and ZnO||LAO. The defects in m-plane ZnO have been systematically investigated using cross section and plan-view transmission electron microscopy (TEM). High-resolution TEM observations in cross section show misfit dislocations and basal stacking faults (BSFs) at the ZnO/LAO interface. In the films, threading dislocations (TDs) with 1/3<1120> Burgers vectors are distributed on the basal plane, and BSFs have 1/6<2023> displacement vector. The densities of dislocations and BSFs are estimated to be 5.1×1010cm-2 and 4.3×105cm-1, respectively. In addition to TDs and BSFs, plan-view TEM examination also reveals that stacking mismatch boundaries mainly lie along the m-planes and they connect with planar defect segments along the r-planes.