A detection device for simultaneous in-situ measurement of dissolved oxygen at different submerged plant leaf-water interface levels. The detection device includes a dissolved oxygen micro-optrode host. A plurality of detection probes are externally connected to the dissolved oxygen micro-optrode host and can extend out probes. The detection device includes a leaf clamp having an upper clamping head, a lower clamping head, a hinged shaft and a clamping handle. Each of the upper and lower clamping head includes a plurality of water passing cavities penetrating through the back and the front thereof. Each of the upper and lower clamping head includes a plurality of slots horizontally extending inwardly of the corresponding clamping head. The detection device includes a plurality of insertion pieces having a probe groove. The detection probe is locatable in the respective probe groove for fixation. The insertion pieces are insertable and fixable in the slots.