Hi I was wondering if anyone has experience teaching economics to high schoolers in China. I am currently planning a curriculum, but I'm not sure what to expect as far as English comprehension, so it's very difficult to pick a book. If anyone can offer advice or recommendations I would greatly appreciate it!

Any high school economics book will do as a start. You won't be able to teach everything, no school ever does, but you need to cover basic ideas.

Nearly all of the economics terms are new to most people, and you will need to make sure they know this core vocabulary. Make sure they know what the words mean in economic terms, as vernacular (and even business studies) definitions can differ. For example, scarcity and shortage may be synonymous in everyday English, but in economics they mean specific things.
The students will also need to understand certain principles. Using case studies, like The Great Depression, might not be helpful as Chinese students are not familiar with it.

You will need to think of more basic, everyday examples. Spoon feeding students with explanations, and ideas that they can picture will help them.
If the students are below IELTS level 4.5, you will face an uphill battle until they can understand enough of your simple explanations to make the necessary connections between ideas and the real world.

You're teaching Western business-economics, right? Practical stuff about how markets work and so forth?

@tigertiger is absolutely correct in that English will be your major problem. You need to keep to Econ 101-Micro Econ and you may never get to Econ 102-Macro Econ.

If you can download or capture videos, try www.mruniversity.com/

If you avoid comparative econ and stuff critical of socialism, you should be okay. Most, if not all Western economists, Classical, Austrian School, Hayek, Mises, and Friedman are taught in China.

Language, concepts and theory, are hard to get across. Try to use examples with math in them. Algebra, called Equations in China, is well known and helps to transmit logic.

You may run into problems when using Arabic numbers. I have one or two PowerPoints to teach numbers. Also several number exercise questions to help them translate to and from Arabic, Roman and Hanzi numbers. PM me.

A good book to help you tech is "Basic Economics for Students and Non-Students Alike" by Jerry Wyant, Kindle $1.99 USD. PM me about this book.

Better book, but usefulness depends on what and how you teach is 'Basic Economics,' 5th Ed.,

by Thomas Sowell, Kindle $23.99 USD.