The lifespan of MCC over China mainland is divided into 7 stages with the features of its energy evolution process discussed in detail.Results show that there exists a deep instable layer below 500hPa during the whole MCC lifespan with the instability decreasing generally and that the moisture and heat flow into MCC from its southwest and south side with the maximum flux being at 900~500hPa.It is also found that the low level jet accompanied with upper-level jet and mid low-level trough is favourable to the formation and development of MCC.