The application discloses a device and a method for picking up top k values from N values. The method comprises: A) controlling a buffer to receive values into a data pool until the number of values in the data pool reaches the predetermined memory size; B) dividing the values in the data pool into a first portion and a second portion; C) discarding the values in the second portion and controlling the buffer to continue to receive values into the data pool; D) repeating steps B to C until the buffer has received all the N values; E) dividing the values in the data pool into the first portion and the second portion until the number of values in the first portion reaches k; and F) controlling the buffer to output the k values in the first portion as the top k values.