The invention discloses a slow release fertilizer for tea trees and a preparation method thereof. The slow release fertilizer for the tea trees is prepared from the following raw materials: urea, potassium dihydrogen phosphate, ammonium chloride, attapulgite clay, boric acid, humic acid, ferrous sulfate, zinc sulfate, ethyl 3-hydroxybutyrate, a catalyst, calcium alginate and microcrystalline wax.According to the method, a product poly-Beta-hydroxybutyrate obtained by enabling the ethyl 3-hydroxybutyrate to react with the catalyst is taken as an inner coating film, and the microcrystalline waxis taken as an outer coating film to coat the urea, the potassium dihydrogen phosphate, the ammonium chloride, the attapulgite clay and the boric acid; the calcium alginate is taken as the inner coating film, and the microcrystalline wax is taken as the outer coating film to coat the humic acid, the ferrous sulfate and the zinc sulfate. The slow release fertilizer for the tea trees obtained by the invention has a good slow release property, can improve the soil structure, and does not cause harm to the environment. In addition, the preparation process is simple and convenient for popularization and use.