In the early Republican period, the national standards and metrology was in an unprecedented mess, which was mainly caused by two following reasons. For one thing, there was no absolute rule for standards and metrology. The government had been failing to unify the standards and metrology since late Qing Dynasty. For another, there were lots of standards and metrology using by other countries, which had been forcedly entering into China because of the gradually open customs and various unequal treaties.

The most important reforms of standards and metrology during Republican period were two metric system leading ones. The first one was AB Plan Blend launched by Warlord Government. It used A Plan (metric system) as direction and considered B Plan (yingzao-kuping units system) as a transition and auxiliary, valuing not only the international integration but also the tradition. However it failed because of political instability and ineffective implement. The second time was the plan suggested by Nanjing Government, using metric system as standards, and Chinese system as auxiliary. This suggestion built on the first one and decided a reasonable and simple conversion rate, “one two three”, between one and the other. Since this time there were effective and well-planned arrangement, the second standards and metrology movements successfully eliminated the Standards and Metrology confusion in the early Republican period and established a good foundation of transferring from Chinese system to metric one.