The invention discloses a method for preparing a willemite mineral collecting agent. The method includes the following steps: using two or three of soybeans, castor beans, tea tree seeds and tea tree bark as raw materials, carrying out drying, smashing and screening, fetching fruit tree bark powder, triethanolamine and water with the mass ratio of 5-8 to 2-4 to 5-10, heating the mixture to the temperature ranging from 120 DEG C to 130 DEG C, leading in nitrogen, stirring to enable a reaction to last for 2-3 hours, heating the mixture to the temperature ranging from 150 DEG C to 160 DEG C, leading in nitrogen, stirring to enable a reaction to last for 2-3 hours, cooling the mixture to the temperature lower than 60 DEG C, fetching filter liquor, carrying out centrifugal separation two or three times through a centrifugation machine, carrying out reduced pressure distillation on supermatant liquor, obtaining a deep yellow concentrated solution, heating the deep yellow concentrated solution in a 60-70 DEG C water bath, evaporating a solvent to be dry, and obtaining yellow powder, namely the willemite mineral collecting agent after complete drying is achieved. According to the method, argillization and dolomite-contained willemite minerals can be effectively collected through the collecting agent.