Is it true that Beijing Huacheng Law Firm sent me a lawyer letter?

and it's true that there will be the seal of the law firm at the signature office. If not, it is a fake lawyer's letter, which is forged.

because the nature of the lawyer's letter determines that its format and content are strict, it can be verified by the contact information written in the lawyer's letter.

If there is indeed an overdue online loan, it is more likely that the lawyer's letter sent is true. If you are not sure whether it is true or not, you can check it through the website of the Lawyers Association.