The invention relates to a frozen trash fish dicing apparatus. The apparatus comprises a fish cube feeding device inclined to a certain degree, a driving mechanism and a cam mechanism; the lower end of the fish cube feeding device is provided with a guide rail vertical to a fish cube feeding direction, and the guide rail is provided with an upper knife rest capable of sliding on the guide rail and a lower knife rest fixedly arranged corresponding to the upper knife rest; the cam mechanism drives the upper knife rest to slide along guide rail, and matches with lower knife rest to carry out cutting; a spring compression mechanism synchronously slides with the upper knife rest, is in contact of fish cubes in advance of an upper knife, and compresses to realize convenient cutting; the lower portion of the fish cube feeding device is provided with elastic baffle blocks opposite to the fish cube feeding direction, the front and back positions of the elastic baffle blocks can be adjusted to adjust the fish cube cutting width, and the elastic baffle blocks have a fish cube buffering effect to prevent fish cubes from being chopped; and the upper knife rest is also fixedly provided with a push block, and the push block downward pushes cut fish cubes to a position below the elastic baffle blocks in order to keep the fish cubes away from the elastic baffle blocks and to make the fish cubes fall into a below discharging hopper.