In 2005, collision resistance of several hash functions was broken by Wang et al. The strategy of determining message differential is the most important part of collision attacks against hash functions. So far, there are only three other message differentials attack published, one of which is 6 bits difference and two are 1 bit difference. In this paper, we propose a completely new attack with 2 bits differential. Our message differential of MD5 generates a collision with complexity of less than 2^41.5 MD5 computations. Although it is slower than the latest best attack, it will be useful in analyzing the security of related applications.