The invention discloses a very soft thick coal seam hold and full-mechanized top coal caving mining method and a top coal caving hydraulic support structure which is applicable to the process requirements of very soft coal seam hold and full-mechanized top coal caving, and the method can form the hold mining process features by using a roller of a coal mining machine to cut and load coal under a top beam of the support, realize the full-closed mining of a working face, and lead the beam end distance of the top beam (the distance between the front end of the top beam and the coal wall when using the coal mining machine to cut and mine) to be close to zero or be a negative value, and a coal shoveling plate is arranged at the front end of a shovel type telescopic beam, thereby being capable of shoveling off top coal under the situation that the coal wall spalling is insufficient, protecting an exposed top plate under the situation that the coal wall is sufficiently spalled and further avoiding the large-area roof-fall accidents, wherein the telescopic stroke of a jack of the telescopic beam is larger than a web of the coal mining machine. The method can realize the full-mechanized mining of a very soft coal seam and has the advantages of low cost, simple process, safety, high efficiency and the like.