Disclosed in the present application are a method and a device for indicating and determining a downlink control information format. The method comprises: when the information bit length of downlink control information for a short transmission time interval is the same as that of downlink control information of a legacy subframe, an information domain carrying an indication that the downlink control information is the downlink control information of the legacy subframe or the downlink control information for the short transmission time interval; after receiving the downlink control information, determining, according to the indication, that the downlink control information is the downlink control information of the legacy subframe or the downlink control information for the short transmission time interval. The present application enables a terminal to distinguish same sized downlink control information of a legacy subframe and downlink control information for a short transmission time interval, and helps to reduce the number of blind tests of the terminal when short downlink control information is transmitted in a legacy control region.