The invention discloses a preparation method for auxiliarily compounding magnetic confined noble metal catalysts through a soft template, wherein ferroferric oxide (Fe3O4) nano particles which are modified through hydrophilic polymers are compounded by adopting a solvothermal method firstly, the surface of Fe3O4 is modified by amphiphilic polymers secondly, and the amphiphilic polymers form a random coil by adjusting the radio of a solvent. Reducing functional monomers and noble metal sources generate a redox reaction on a random coil template, and noble metal nano particles and functional polymers are deposited on the surface of the Fe3O4 at one step, thereby forming a catalyst. The preparation method for auxiliarily compounding the magnetic confined noble metal catalysts through the soft template forms noble metal nano particle confinements on a polymer structure and deposits the obtained structure on the surface of the Fe3O4 at one step at the same time, and forms a magnetic confined noble metal catalyst with a core-satellites structure, thereby preventing a migration reunion phenomenon of the noble metal nano particles during the catalytic process, greatly simplifying synthetic process of the magnetic confined noble metal catalysts, and being beneficial for large scale industrial production.