The invention discloses a preparation method of a walnut diaphragma juglandis lipid-lowering health care tea. The preparation method comprises the following steps: 1) pretreatment of walnut diaphragma juglandis: selecting fresh walnuts with intact fruit, no worm damage and no mildew, washing, removing peels, denucleating, picking out the walnut diaphragma juglandis in walnut kernels, and airing for standby use; 2) preparation of a walnut diaphragma juglandis extracting solution; 3) sunning; 4) green leaf cooling; 5) green leaf rocking; 6) killing out; 7) twisting; 8) pilling; 9) drying; and 10) repeatedly operating the steps 8) and 9) for five to ten time to obtain the walnut diaphragma juglandis lipid-lowering health care tea. The walnut diaphragma juglandis extracting solution is prepared by using the walnut diaphragma juglandis, and is uniformly sprayed to tea leaves in the sunning, twisting and piling processes, so that the fragrance of the finished product health care tea can be further promoted; and the contents of lipid-lowering active substances of the tea leaves can be obviously improved, and a lipid-lowering effect is strengthened.