An　Space　Time　Block　Code　Quasi-orthogonal　Time　Division　Multiplex　(STBC-QOTDM)　for　multi-input　multi-output　(MIMO)　system　was　proposed,　in　which　the　QOTDM　sample　sequences　are　STBC　before　transmission.　Based　on　the　integral　relationship　among　the　modified　Gaussian　Q　function,　the　probability　density　function,　and　the　characteristic　function　of　the　channel,　a　closed　form　solution　for　symbol　error　probability　(SEP)　of　STBC-QOTDM　due　to　the　sample　errors　over　spatially　correlated　fading　channels　was　derived.　This　form　can　be　used　to　evaluate　the　SEP　performance　of　the　STBC-QOTDM　system.　Finally,　Monte　Carlo　simulations　of　the　system　demonstrate　the　correctness　of　the　obtained　closed　form　solution.