Based on the current situation where natural gas has become more and more popular, this study combines internal structure and working principle of diaphragm gas meter, and studies a rapid error-calibrating technology for diaphragm gas meter with sonic nozzle based on rotary equivalent volume. On the basis of existing standard apparatus, an overall automatic verification system of auto-detecting control system is designed. The automatic verification system shortens detecting time at the lowest-capacity point and improves efficiency of verification.