Abstract: Due to the limitation of a single short-circuit detection feature, the short-circuit protection method of a low-voltage AC system based on the over-current principle has been unable to meet the requirements of operation protection under complex working conditions. With the availability of flexible technologies such as distributed photovoltaic and energy storage, low-voltage protection technology has faced new hurdles. Therefore, a node-autonomous fast short circuit protection method for distributed photovoltaic low-voltage AC systems is proposed. Firstly, the characteristics of the branch state are constructed using the instantaneous amplitudes of short-circuit current and voltage, and the early detection technique of short-circuit state is investigated. Secondly, the polarity information of the short-circuit current in each branch of the same node is introduced, and the short circuit branch protection decision mechanism based on the direction correlation identification of the short-circuit current is designed. Finally, the protection experiment of the low voltage physical experiment system and its simulation model are carried out. The experimental results show that the short circuit of both the traditional and photovoltaic branches can be detected within 0.5 ms. The protection response ranges between different nodes are reasonably matched, and for the short circuit at the near end of the outlet of the same node, whether the protection is triggered can be accurately determine in each branch within 1 ms of the short circuit, thus achieving selective protection. The protection method does not malfunction under the disturbance of various source load operating conditions. The research results have high theoretical and engineering value.