終於找到了

一直在google, 總算找到官方解釋了，說隻要符合six year limit exemption的要求，無論是什麽簽證，或者人不在美國，都可以申請新的H1簽證。

http://www.nafsa.org/_/File/_/UCSIC_Guidance_H-1B_Beyond_Six_Years.pdf

In sections 106 and 104(c) of AC21, Congress provided exemptions from maximum stay rules for certain H-1B aliens who were being sponsored by employers for permanent residence and were subject to long delays either for government processing or for visa numbers. The relevant subsections emphasize exemption from the maximum admission under INA section 214(g)(4). Congress did not restrict eligibility for additional periods of admission beyond the maximum six years to only requests for extension of stay.
A qualified alien need not be in H-1B status in order to benefit from sections 106 and 104(c) of AC21. The alien may obtain such additional periods of H-1B admission through a petition to change status from another nonimmigrant classification, or through H-1B visa issuance at a U.S. consulate (unless visa exempt) and admission from abroad.