Baking powder is a commonly used baking accessory to make baked goods fluffier and more fluffy. If you don't have baking powder, consider using the following substitutes:

1. Baking soda: Baking soda is also a commonly used baking accessory that reacts with acids to produce carbon dioxide, which acts similarly to baking powder. Mix the right amount of baking soda with an acidic substance (e.g. vinegar, lemon juice, yogurt, etc.) and add it to the cake batter and mix well.

2. Baking powder: Baking powder is a yeast-based baking accessory that allows baked goods to ferment and expand, achieving a similar effect to baking powder. Add the right amount of baking powder to the cake batter and mix well.

3. Double baking powder: Double baking powder is a baking accessory with the dual role of baking powder and baking powder, similar to the amount of baking powder and baking powder. Add the right amount of double baking powder to the cake batter and mix well.

It is important to note that the method of use and dosage may vary between substitutes, and specific use should be adjusted according to recipe requirements and your own experience to ensure the quality of baked goods.