The invention relates to a high-voltage direct-current power transmission technology training system combining theories and practice, which comprises an off-line direct-current power transmission training system (7), an off-line direct-current power transmission training system (10) based on a U3 platform, a direct-current power transmission simulation system (3), an on-line/off-line training changeover device (2) and a user terminal (1), wherein the user terminal (1) is respectively connected with the off-line direct-current power transmission training system (7), the off-line direct-current power transmission training system (10) based on a U3 platform and the direct-current power transmission simulation system (3) through on-line/off-line training changeover device (2). The invention has the advantages of abundant materials, and good interaction and expandability, and adopts a modularized design structure which comprises a right management subsidiary system, a user management subsidiary system, a direct-current power transmission system and a fault demonstration subsidiary system. The direct-current power transmission simulation system has strong operability, is vivid and lifelike and can truly simulate the practical characteristics of a direct-current power transmission system; The training system of the invention not only can realize the plentiful and abundant high-voltage direct-current power transmission technology theoretical training based on a multimedia courseware, but also can realize the vivid and lifelike practice training based on the direct-current power transmission simulation system. The invention can meet the requirements of scientific, effective and total training of high-voltage direct-current power transmission technicians.