The invention provides a double-deck block for spreading crossing rack ropes. The double-deck block comprises two oppositely arranged side plates, a lifting ring, an upper wheel, a lower wheel and two fast pressing devices. A lifting ring shaft is sleeved with the lifting ring body, the lifting ring shaft is installed in lifting ring holes of the two side plates, an upper pulley is installed on an upper wheel shaft rotatably, the upper wheel shaft is contained in an inclined wheel groove detachably, a lower pulley is installed on a lower wheel shaft rotatably, and the lower wheel shaft is installed in lower wheel holes of the two side plates. The two fast pressing devices are installed on the two side plates respectively, pressing handles are installed on the plate bodies of the side plates, moving parts are installed on lock covers, and the lock covers are installed on the side plates rotatably. The invention further provides a using method of the double-deck block for spreading crossing rack ropes. The mode that the upper wheel goes in or out the block is adopted for the double-deck block for spreading crossing rack ropes, the lock covers can be opened fast to release the upper wheel just by pulling the handles of the fast pressing devices, then, the crossing rack ropes can be transferred from the upper wheel to the lower wheel, and the double-deck block is easy and convenient to operate and high in construction efficiency.