Determining the nature of suspicious audit matters by law is an important part of auditing by law, and the simple application of the clause of law to determine the nature of suspicious audit matters may bring regulation antinomy. This paper puts forward a theory framework which explains the possible regulation antinomy and salvage mechanism for auditing by law. The most direct path for determining the nature of suspicious audit matters by law is to apply the clause of law strictly, and this model may bring out two kinds of regulation antinomy, one is legal but not reasonable, the second is reasonable but illegal, these two categories of inappropriate qualitative analysis are not conducive to the audit objectives. Therefore, auditor must determine whether regulation antinomy exists, and succour the existent regulation antinomy, the salvage mechanism includes purpose expansion and purpose shrinkage. Under new normal period, there is a new strategy of governing the country, and the national audit should serve the national governance better and judge the regulation antinomy and respond to them in accordance with law.