The invention discloses a read-out circuit and a working method thereof, relating to a read-out circuit and a working method thereof. The read-out circuit comprises M columns*N rows of pixel circuits,N rows of row level test resistance circuits, M columns of column level test resistance circuits and M columns of column level read-out circuits, wherein both M and N are natural numbers, M is greater than or equal to 2, and N is greater than or equal to 2, the row level test resistance circuits, the column level test resistance circuits and the columns level read-out circuits are all connected with the pixel circuits, the column level test resistance circuits are connected with the column level read-out circuits, the column level read-out circuits comprise test column secondary circuits, andthe column level read-out circuits are further connected with a current source. Functions of all columns and rows of the whole read-out circuit can be tested without an MEMS sensor, further, more accurate MEMS resistance can be acquired when the MEMS sensor is available, the test result is more accurate, and the test efficiency is improved.