The invention discloses a chain transmission type synchronizing mechanism and a plate shearing machine and relates to the technical field of machining. According to the chain transmission type synchronizing mechanism, two single-row chain wheels are installed on a first installation plate, and two double-row chain wheels are installed on a second installation plate; a transmission chain is engaged with the two single-row chain wheels and one double-row chain wheel, and the two ends of the transmission chain are connected with the two ends of a double-shaft air cylinder piston rod correspondingly; a transmission chain between the two single-row chain wheels is connected with a first sliding platform through a chain connecting base, and the first sliding platform can slide along a guide rail arranged on the first installation plate under the action of the transmission chain; a synchronizing chain is wound on the other double-row chain wheel, and the double-row chain wheel is connected with a second sliding platform through a chain connecting base; the second sliding platform and the first sliding platform can move synchronously under the action of the synchronizing chain. The plate shearing machine is provided with the chain transmission type synchronizing mechanism. The chain transmission type synchronizing mechanism is higher in universality and capable of being adapted to installation in various directions.