You will get an immigration visa alright, since you have married for two years and have a kid together, just don't set your heart on getting it fast; apply from another country won't speed up the process either. So you should just prepare your documents, imagine there must be lots and lots, and send application in and wait patiently while prepare your mind to the following facts you will be facing when you reach US:
1, Under current brutal economic environment, jobs are very hard to find. Some of my acquaintances haven't had a stable job for the last two years, regardless of their MBA or CFA status. Of course low wage jobs are not too hard to get if you don't mind working in grocery stores, hotels, fast food restaurants, etc.
2, Daycare for kids under age 5 will cost you around us$1000 a month depending on what area you live in (80% of the grandmas and grandpas will not babysit their grandchildren day after day), this amount is roughly what your paycheck amounts to if you work a low wage job. Yuantongsi is right about public school education, it just that there is always a BUT, you have to pay the costs of some school activities like field trips, school festivities, after school programs, and so on. By the way, Kindergartens are only funded half day, so if you choose to put your kindergartener there all day, you have to pay for it, it's about $5000, and if you can't pick up your child from school at 3:40PM, you pay for after school care, about $20/day.
3, There is no affordable medical coverage if you don't have a job. Without insurance, a simple doctor's office visit for 15 minutes will cost you at least $200. So if you have a young child, you must take medical spending into serious consideration.
4, US is a very suburban country, if you come from a noisy, crowded city (like any chinese city) in China, it will take you a long while to adjust to the quiet life in the States (I presumptuously assume you are not going to New York city), and the typical loose connections between people, even between friends will make that adjustment even harder.
I am not trying to curb your enthusiasm on living in a totally different place, just want to let you understand some of the situations you may encounter when you get there, plan/understand it ahead will make your transition/adjustment a bit easier.
Wish you a speedy success, and good luck!