Almond powder takes bitter almond which is full, big, mildew-free and moth-eaten as raw material to remove impurities such as sediment and broken kernels. Soak bitter almonds in warm water for 16 ~ 18 hours, take them out, boil them in boiling water for 10 minutes, and rub off the almond skin after cooling. Soak almonds in cold water for 4-5 days, and change water 3-4 times a day until almonds have no bitterness. Take out the almonds, drain the water, put them in an oven for drying, then grind them and pass through a 150 mesh sieve to obtain almond powder. However, I also suggest that you still use the one you bought. Need a lot of professional tools to do it.