Abstract: Law origin status of commercial unwritten law has been admitted in America commercial law, and gained law status by standard item. Origin status of commercial unwritten law has deep theory base. Respecting businessman meaning self-government is its subjective theory base. Respecting businessman behavior mode is its impersonality theory base. Respecting businessman benefit-gaining essentiality is its economy theory base. Maturity court and lawyer system is its support base. To build business law accord with the situation of our country and economy development law, we must affirm origin status of commercial unwritten law in some scientific way.