The statistics are pretty easy to look up and yes the USA does have a lot of people in prison, but they were tried and convicted, which is considerably different than China's approach to criminal justice. Are there innocents in prison here, yep, but a very small percentage and they have legal access and recourse, which again, isn't the case in China for many.
Speaking of statistics, have a look at how many immigrate to China, compared to those that leave and never come back. Guess where they go, by an overwhelming majority? Over 45 million international migrants lived in the United States in 2013. Yet only 850,000 people living in China were born in other countries. Hummmmm. Wonder why. The USA has been the major country for immigration since it's founding.
In fact it's Chinese, born outside the country that are moving to China, making it the fourth largest emergration country in the world, but no other ethnics are coming to China. To further these facts, the biggest movers are within China itself, with migrants moving to find better work, from rural to urban areas.
Things are changing within China and they'll have to work on a new immigration policy soon. China has little experience with immigration and has no special law regulating transnational migrants. Of the most recent statistics, about a 1/2 a million people immigrated to China, but only 10% of these for employment. Korea, Myanmar and Vietnam are the big contributors to this list. This is especially true with respect to the granting of "eligible status", which is still under strict policy control. There is a very limited quota of Chinese "green cards", or permanent residence permits for foreign citizens, and applications for such permits are usually influenced by politics, in which they are primarily issued for "international friends" of the Communist Party instead of for international immigrants.
China is not exceptional in facing and dealing with illegal migration issues, which are a serious problem for many countries. According to the International Organization for Migration, "most States in the world (and not just in the developing world) lack the capacity to effectively manage the international mobility of persons today, not to mention respond to new dynamics". Even the United States, which defines itself as a nation of immigrants, still has to face "an estimated 11 million undocumented immigrants. Some crossed the border illegally. Others avoid immigration laws by overstaying their visas". Europe is also facing an increasing illicit migration problem, with “an estimated 400,000 people entering Europe illegally each year, being compounded by recent events in the eastern Med.
My point is China is behind the "8 ball" on many levels, not only immigration, but social values, legal concerns, monterey and industrial market fair play, acceptance of certain "inalienable" rights, etc., that much of the first world countries take for granted. If we organize a demonstration against our governments, we don't expect to spend the next ten years in prison without charges or a trial, just for calling the president a butt head, but try that in China and there's a very strong likelihood you will. China's rise has been exceptional, but to profit at the expense of the people's freedoms, the quality of the land, sea and water, etc. is a terrible price to pay and I hope your country learns faster than the others that have been its shoes did.