It is stated that image transmission and access need the throughout of the system exceeding well over Gb/s,if conventional optical code division multiple access system is used as transmission system. it will be very difficult to realize because of the speed limitation of current opto-electronic devices,and the requirement to opto-electronic devices will be very high. The solution is adopted parallel transmission system based on optical code division multiple access. However,the signature of the parallel transmission system is a two-dimensional optical orthogonal signature patterns different from conventional signature sequences. Aiming at the problem that the construction of the maximum capacity of the optical orthogonal signature patterns (optimal optical orthogonal signature patterns) is lacked now,a novel construction algorithm based on block design is presented. The idea of the algorithm is based on the relationship between difference sets and optical orthogonal codes. If the concept of difference sets and block design can be extended to two-dimensional space,then according to the relationship between two-dimensional difference sets and optical orthogonal signature patterns,the construction of optimal optical orthogonal signature patterns can be achieved. The procedures to construct optimal optical orthogonal signature patterns are explained in detail. Simulation based on the algorithm is done. The simulating result shows that this algorithm can construct optimal optical orthogonal signature patterns effectively.