Abstract: In Ningbo, Shanghai and other cities, an assurance called petty loan garantee of S&T SMEs, which has effectively relieved their financing problems. This article analyses the main practice of Ningbo and Shanghai's operating the petty loan assurance. It also points out the main problems, such as the not-fully-established system of the insurance marketing, the difficulties in solving the reinsurance problem, the insufficiency in corresponding supportive policy, and the need to improve the social credit system. In the end, this article proposed some suggestions for the future development.