I want to open a children's photography studio in Tongzhou. I don't know how much I need to invest in the early stage and what preparations I need to make.

What kind of studio? The low cost is to rent a small scroll (depending on the geographical location, the price varies greatly), buy a mid-range camera (6000~ 15000), buy two soft boxes (4000), buy a computer (4000), buy some background cloth (500), and buy some props for taking pictures, such as plush toys and big ones.