The present invention relates to a door latch system, more particularly to a door latch system which includes: a stopping lever unit rotatably installed in any one of the main locking member and the sub-locking member; a stopping threshold formed in the other one of the main locking member and the sub-locking member wherein a stopping protrusion is being caught; and a locking plate slidingly installed in a housing for rotating the stopping lever unit, wherein a lever guide portion is formed in the locking plate, and a guide bar is formed in the stopping lever unit, so that the rotation of the stopping lever unit is accomplished as the guide bar is guided by the lever guide portion, and when the stopping lever unit is caught by the stopping threshold due to the sliding of the locking plate, the main locking member and the sub-locking member are sliding together, and when the stopping lever unit is separated from the stopping threshold due to the sliding of the locking plate, only the sub-locking member is slided, so that the structure for connecting the main locking member and the sub-locking member becomes simple, and the durability of the device is enhanced as well.