The invention provides a method for an iSCSI block direct storage to support a change of a video space. The method comprises the steps as follows: stopping storing after receiving a message carrying shrinkage capacity L; and determining an initial position B of a first data unit as the shrinkage initial position if the residual space from the first data unit at the back of a current read-in data unit to a tail part of the resource is not less than the shrinkage capacity L; determining the initial position C of the first data unit as the first shrinkage initial position if the residual space from the initial position of the first data unit at the back of the current read-in data unit to the tail part of the resource is less than the shrinkage capacity L, and determining the position from the C position to the tail part of the resource as a first shrinkage capacity L, and further determining the initial position A of the first data unit of the resource as a second shrinkage initial position, wherein the shrinkage capacity from the A position is L2, and L1 plus L2 equals to L; returning the shrinkage initial position and the shrinkage capacity starting from the position to IPS storage equipment. The method and the device of the invention well support the storage shrinkage.