Through and comprehensive tests are necessary to ensure complete stability and reliability of AUV, due to the high risk and consumption of in field testing, onshore testing technology for AUV is proposed. Rudder load simulator plays an important role in the onshore testing of AUV. In this paper, the design and development of a rudder load simulator was discussed. Rudder load calculation method during the onshore testing, system scheme, control structure, controller design and control parameters optimization are studied in detail. Several demonstration tests results demonstrated the performance of the rudder load simulator.