Abstract: There are many ways to attack blockchain and applications. We propose a DDoS attack model and establish two indicators to measure the impact of DDoS attacks on the performance of blockchain networks. Utilizing Hyperledger Fabric to construct the experimental environment, 6 experiments with different number of attacking peer nodes were designed to simulate DDoS attack events. Another experiment simulated the whole process of DDoS attack from beginning to end. Experimental result shows that blockchain network is indeed vulnerable to the potential risk of DDoS attack. The internal peer nodes of blockchain have their probability of becoming the DDoS attacker. Even a small number of attackers (ratio below 33% or 51%) could attack blockchain. The main destruction of DDoS attack is delaying the service time of transaction, reducing the service throughput as well as performance.