US visa-free requirements:
1. Visa types that can be applied without face-to-face signing: when applicants who have obtained business (B 1), tourism (B2), studying abroad (f), exchange visit (j), short-term work (h) and employees of multinational companies (l) apply for visas again;
2. The last visa obtained is still valid or expires within four years from the last visa;
3. The applicant's current visa application is the same as the last visa type;
4./kloc-applicants under 0/4 years of age and over 80 years of age can sign in person.
Can't apply for visa-free face-to-face visa:
1, exceeding the 4-year visa-free time limit;
2. The visa type applied by the applicant this time does not match the visa type obtained last time;
3. When the visa was obtained last time, it was revoked;
4. The last visa was refused.