An in-wall feature detection device of mutual capacitive technology comprises a housing, a detection baseplate, and at least one capacitive sensing baseplate. The detection baseplate is disposed in the housing and has a central processing module and a capacitance value conversion module and is electrically connected to at least one display module. The capacitive sensing baseplate is provided with driving modules and receiving modules, the driving and receiving modules are arranged in a crisscross manner and electrically connected to the capacitance value conversion module. The in-wall feature detection device is capable of using an electric field change between the driving and receiving modules to determine whether there is a blocking object in a wall, and further generating a corresponding light signal through the central processing module to display a shape of the blocking object. Thereby determining a position and the shape of the blocking object during construction.