The present invention relates to a small spatial sound source orientation detecting device, including a circuit board; three or more MEMS acoustic-electric transducers fixedly arranged on the circuit board and centrosymmetric distribution. The distance between adjacent MEMS acoustic-electric transducers is not more than one-half of the shortest wavelength of the sound source signal; and a micro-control unit, each MEMS acoustic-electric transducer is electrically connected to the micro-control unit respectively. The micro-control unit is to obtain the orientation information of the spatial sound source based on the acoustic signals collected by three or more MEMS acoustic-electric transducers. The present invention also provides a spatial sound source orientation detection method. The small spatial sound source orientation detecting device of the present invention has an ultra-small space size, and can accurately detect the orientation information of the sound source.