To improve processor’s computation capability heavily,one multi-core system with 5 CPUs is designed and H.264 is decoded on it parallely.One CPU is used to lead the other four CPUs.Five CPUs share one 32 KWord SRAM.Any two CPUs can communicate point to point through mailbox,semaphore,hardware lock.When decoding H.264,the leading CPU is used to parse the bit-stream and calculate the intra prediction mode,motion vector,boundary strength.Then,the decoded data is saved to shared SRAM.Other four CPUs fetch and solve one macro-block line each time.The simulation result shows that using the line parallel decoding algorithm,the five-cores system can achieve about 3.6 times acceleration than two-cores system.The line parallel decoding algorithm can also be used on other video protocol and it is universal.