An optical detection device of detecting a target container includes a linear light source, an optical sensor array and a processor. The linear light source is adapted to project a long strip illumination beam onto the target container. The optical sensor array includes a plurality of sensing units arranged as a long strip adapted to receive a long strip detection beam reflected from the target container. The processor is electrically connected to the optical sensor array. The processor is adapted to analyze intensity distribution of the plurality of sensing units to acquire a relative distance between the optical sensor array and a rim of the target container.