I asked the American immigration agent before, but I didn't apply for immigration. Will the American consulate find out?

No. According to the information, if you don't apply for immigration, you shouldn't go to the local public security department to apply for a passport. If you register in the American embassy, you don't need to fill in the information application, ID number, address, work unit, rank, etc. , and will not leave a true identity. You only ask the intermediary if you don't apply for immigration, the American consulate will have no information and you can't find it.