A spliced detection apparatus for simultaneous wide-range in-situ detection of dissolved oxygen in a sludge-water interface of the present invention comprises a dissolved oxygen shimmer host, several detection probes, a casing and detection kits, several vertically through seat chambers being disposed in the casing, the detection kits can be placed and fixed in the seat chambers, the detection kits may be placed on the sludge-water interface, and each detection kit is provided with a vertically through water passage chamber, while the front side face and the back side face of the detection kit are respectively provided with several front slots and rear slots horizontally extending into the detection kit respectively, the detection apparatus further comprises tabs, with probe grooves being provided on the tabs, each detection probe can be put into the probe groove of the corresponding tab and fixed therein, the tabs may be inserted either into the front slots or the rear slots and can enable the probe tips of the detection probes to be placed in the water passage chamber, the detection apparatus can carry out simultaneous wide-range detection of the dissolved oxygen at different heights and horizontal positions of the sludge-water interface, and thus is quick and convenient for use.